Microatx dimensions. The device of computer power supplies and the method of testing them Atx holes

Computer technology is evolving. The shape of the devices, their dimensions and technical characteristics are changing. Today we will consider such a concept as a form factor, and its ATX version is the most popular and demanded.

Form factor

To get to the topic of the article, you need to understand the basic concept. Form factor is standardization in relation to IT equipment. Using it, you can determine the size of the device, the main technical indicators, the presence of additional parts, their location.

Now, speaking of the form factor, people remember the motherboard. Previously, the term was applied to phone cases, communication equipment and other PC components.

Given that the form factor is a standardized concept, it is referred to as a recommendation parameter. That is, thanks to the index, which denote a certain form factor, it is possible to designate the required and additional parameters. Developers try to take the standard for granted and follow it when creating the appropriate component.

Variety

The ATX form factor is not the only standard for components. But it was this option that became in demand for the mass production of PCs. The world saw it for the first time in 1995, and Intel became the manufacturer of this architecture. Previously, the XT, AT, and Baby-AT standards existed and were implemented by IBM since 1983.

The ATX form factor influenced the emergence of modified standards. Abbreviated formats began to appear, with fewer slots and compact dimensions. By 2005, a mobile standard was developed, optimized for processors.

Office computers also began to be equipped with various components of certain standards. Boards began to appear that were used in complex industries. Such modifications of the standard have become known since 2004. ATX form factor reincarnated as SSI CEB, DTX, BTX, etc.

ATX

This form factor became popular back in 1995, but has been most widespread since 2001. The standard has become dominant in PC manufacturing. It affects not only the size of the board or other component. ATX dictates the PSU standard, PC cases, the placement of slots and connectors, the shape and location of the slots, the PSU mount and parameters.

Intel has long pondered how the continuation of the AT form factor should be. By 1995, the developers introduced the brand new ATX standard. In addition to this company, other manufacturers who supplied OEM equipment were thinking about changing the outdated standard. After that, the new standard was picked up by those who supplied motherboards and power supplies.

Over the entire period of its existence, 12 specifications have been released. The ATX form factor has standard dimensions: in millimeters - 305 x 244, in inches - 12 x 9.6. Mods that were released under different names were developed on the basis of ATX, but had differences in port placement, overall dimensions, etc.

So, in 2003, Intel wanted to implement BTX. This new standard cooled the PC system unit more efficiently. The developers wanted to slowly remove from the markets ATX, which maintained high heat inside the system unit. But even such a danger as overheating of the entire system did not contribute to successfully changing the format to BTX.

Most manufacturers refused to distribute it, since reducing the power dissipation showed positive results, and in the future it was still possible to achieve good results when cooling the case and without changing the standard. As a result, by 2011 it became clear that there was no need to replace the ATX form factor.

Major changes

It was not worth waiting for such a successful invention in this area. The user received drastic changes regarding the previous version of AT. The motherboard began to supply power to the processor. Standby power is supplied to it even when it is turned off. The motherboard provides the functioning of the control unit and some peripheral devices.

It became possible to replace the fan with a larger one and place it on the bottom of the power supply unit. The air flow became more powerful and covered more elements in the system unit. The number of revolutions changed, and, accordingly, the noise. Over time, there has been a trend towards placing the PSU at the bottom of the case.

Nutrition

The change in form factor brought a change in the format of the power connector. This was caused by the fact that in the previous format, two similar connectors were connected to unsupported slots, which caused the system to crash. In the process of increasing power consumption, it was necessary to increase the number of power contacts. The developers started with 20, later there were more of them, and additional connectors appeared.

Interface panel

The interface panel has become freer. Previously, there was a slot for a keyboard, and expansion cards were installed in special holes. The ATX form factor added space for a communicator to the keyboard slot. The free area was occupied by a rectangular "slot" of a standardized size, where the developers placed the necessary slots.

Initial power supply

In addition to the fact that there is an ATX form factor motherboard, you can also find the standard. Since the development of the format lasted nine years, during this time the developers tried not only to change the connector, but also to make it compatible with the previous forms.

So, initially, a connector with 20 power contacts was used. This option was popular before the advent of motherboards with a PCI-Express bus. Then a 24-pin connector appeared. For this option to be supported by previous versions, the "bonus" 4 contacts could be removed, and the board would work with twenty.

Processor changes

When new Pentium 4 and Athlon 64 processors began to appear, the standard had to be revised to version 2.0. So, motherboards began to require 12 V for the main bus. The power supply, the ATX form factor of which was also updated to the second version, was supposed to receive an additional connector. So there was an additional connector for another 4 pins.

After that, options with complex contacts began to appear. For example, a 24 + 4 + 6-pin connector has become in demand for motherboards that have received several PCI-E 16x ports. And the 24 + 4 + 4-pin actually had an additional 8-pin connector, which consisted of two 4-pin slots. Thus, it began to be used for motherboards that had high energy consumption.

This decision with the combination of two 4-pin connectors was caused by the fact that the user does not deprive the user of connecting the model to older motherboards. So, one connector was detached from the other, and we got a 24 + 4-pin wire.

Frame

In addition to the motherboard and power supply unit, the case also has a certain standardization. The ATX form factor in this case is the most modern and is suitable for motherboards of the same format. Such a housing allows for easier access to the entire inner periphery. Has excellent ventilation inside. Allows you to install more than one full-size board.

Despite the same names, it can fit a micro-ATX motherboard. We will briefly discuss this standard further.

Compact version

The micro-ATX form factor appeared a little later than the main standard - in 1997. The motherboard of this format is 244 x 244 mm. The variant was developed for processors with the already outdated x86 architecture.

During the development process, it was decided to maintain electrical and mechanical compatibility with the previous standard. As a result, the main differences remain the dimensions of the boards, the number of slots and integrated peripherals. Micro-ATX is marketed with an integrated graphics card, thereby indicating the intended purpose of this standard. PCs with this form factor are suitable for office work and are not designed for gaming projects, since the integrated video card is mediocre.

Other options

In addition to ATX and micro-ATX, there was a mini-ATX form factor, which is nowhere to be found anywhere else. Its dimensions are 284 x 208 mm. FlexATX also appeared, which measured 244 x 190 mm. This modification is flexible and allows the manufacturer to independently solve many problems.

So, he can choose the size and location of the PSU. Participate in changes related to new processor technologies. But even this variant could not “fight” with ATX and remains in the background.

Choosing an ATX case

If the theater begins with a hanger, then a computer - certainly from the case (the case of the system unit). It largely determines the appearance of the computer (as a system), and it is with it that the acquisition of a new computer begins. The exception is special long dual-processor boards (they have an increased size) or the new "non-standard" AMD Athlon processor, for which a power supply unit of at least 300 W is recommended (230 W is sufficient for ordinary ones; perhaps after AMD switched to processors with built-in L2 cache, the problem will be solved).

This article was based on material that I collected before purchasing a new ATX case. I hope the readers find it useful. The fact is that if, for example, there are reviews and conferences on processors, from which you can learn how to overclock / cool, and which series are better to chase and a lot of details, then there is silence in the cases. Naturally, the selection criteria are subjective.

Of course, we will talk about a home computer, and by no means an office or server computer. Further, the preference is given to cases with ATX power supply over the obsolete AT power supply. Finally, only high-quality products are considered ("I love it when the iron is right"), far from cans :)

Note that the case (here and below the system unit) is called in English Case(case) and sometimes Chassis(chassis), although the latter is more appropriate in relation to the load-bearing part of the hull. These terms can be found in the offers of sellers or on the websites of manufacturers.

What is chosen

Let's first consider the main parameters for choosing a case (they are discussed in more detail below).

• Type of shell: desktop or tower
• Tower type... If the user has chosen a tower, then further he chooses one of its four types, differing in height
• Number of compartments, both indoor and outdoor. This number is important for the scalability of the system.
• Case workmanship... Here, important parameters such as steel thickness, rigidity, prevention of radiation outward
• Convenience of the case... Parameters of this kind include, for example, the execution of buttons (so as not to accidentally press them), and the ease of opening the case. The "hidden" parameters include the location of the power supply, the availability of space for additional fans
• Case design... Despite the subjectivity, this parameter is very important, because If you like the cabinet, it involuntarily creates a pleasant working environment. Some manufacturers produce several modifications of cases that have the same parameters listed above, but differ in design. An example is the presence of a door on the front of the case, the placement of light indicators, their shape, color of the case, etc. Further, one likes strict forms, while the other likes futuristic (note that life in fading Macintosh was inspired by the unusual design of iMac cases made of translucent plastic)

• Additional features... An example is sleep button, IR transmitter window
• Type of food... For home computer are mainly used AT and ATX(Latin letters). ATX is a newer standard and has significant advantages over AT. Accordingly, it is this type of power supply that the motherboard usually has. There are chassis and motherboards with combined power supply, but this is of interest only for use with legacy hardware.
• Power supply power... There are several standard power ratings. The most common are 200, 235 and 250 VA. For the possibility of expansion, as well as due to the increase in power consumption of graphics accelerators, it is useful to have a headroom
• Power supply quality... To a large extent determines the durability of other components. When a problem occurs on the side of the power supply, the latter are difficult to diagnose

Case type and number of compartments

Desktops & Towers

Typically, the body has the shape of a parallelepiped, with two pronounced large edges. A sort of flattened threefold cube. Depending on whether these edges are located horizontally or vertically in working position, the housings are divided into two large classes.

Desktop(desktop). Literal translation - desktop. The case is placed on the table with a large edge

Tower(tower). Large faces are arranged vertically (see first two figures)

The inconvenience of a desktop

The desktop appeared first, but now it is clearly outdated for the following reasons. Displays used to be small (with 14 "and 15" screens) and were placed on the desktop to save desk space. If you put a modern large (17 "and 19") display on the desktop, then the comfortable position of the eyes will be disturbed. The point is that the user must look at the screen from top to bottom. Namely, the top edge of the screen should be several centimeters below eye level, and the screen itself should be turned perpendicular to the gaze. This is explained by the fact that the eyelids must be half-closed, otherwise the moisture in the eye will dry out. It is not for nothing that in some computer tables the display stand is made downward and has a slope.

Placing desktop and display separately takes up too much space. In addition, it is inconvenient to remove a heavy display (and at the same time still find a place where to put it) in case of need to open the case.

Now desktop owners place a printer on it. However, it does not look aesthetically pleasing on such a "pedestal". In addition, the freestanding printer and tower take up roughly the same footprint as a desktop.

The tower is devoid of all these shortcomings. In addition, if there is an external modem (as well as a telephone or an external device of a similar size), then it is conveniently placed on the upper edge of the tower.

Note that the desktop can be put on its side, turning it into a tower, but such a replacement will not be complete. First, it makes it difficult to open the case. Secondly, not all drives work well with removable drives in an upright position. For CDs, you have to rotate the petals that hold them, which also complicates the job. Therefore, below we will consider exclusively the towers.

Choose turret hulls

Tower types

Some users, seeing a neat little case, exclaim: "how good it is for the home." In fact, the opposite is true: the home computer needs expandability. If we mean a home computer as a universal computer, not a game console!

The towers are divided into four subtypes, differing in height. In ascending order it is - micro(micro), mini(mini), midi(midi, middle - middle) and complete(big, full). For most enclosures, the "classifier" is the number of large external bays as shown in the table below (although there are exceptions).

Recall that the case has a number of large (5.25 ") and small (3.5") external compartments ( bay, read bay), facing the front side. They insert those internal devices to which access is required during operation: floppy disk drives (floppy drive) and compact discs (nowadays, cases where floppy disks are inserted into a slot have become widespread, but in principle it does not matter).

In the traditional design, the bays are located on top, with large ones higher than small ones (in futuristic cases, everything can be the other way around).

Optimality of the midi tower

Full tower designed for servers, and bulky (in height), redundant and expensive for a home computer. Complete towers usually have a door that covers the compartments and buttons. Note that if there is room under the table, then the full tower is a more interesting choice than the micro tower.

Micro tower has an insufficient number of compartments. In addition, heat dissipation is poor in micro cases. Excess heat has an extremely adverse effect on all internal components without exception.

Therefore, the most popular mini and midi towers. The midi tower with its large number of compartments is preferable. Here are the devices that require large bays:

• CD and CD-RW drives... Note that the CD drive is required. CD-RW drive is convenient for archiving and transferring large amounts of data. Note that modern CD-RW drives have a fairly high read speed and completely replace a "blank" CD drive.
• DVD drive... DVDs are gaining popularity as they are much more spacious than CDs. They are mainly used for the purposes of high-quality video and placement of large software products. DVD drive reads CD discs, so this drive is a more versatile device
• Frame for hard drive... Convenient for users involved in video editing and photography. A second, high-capacity disk is placed in it, which is turned on with a foreign key only when necessary. The disc fits in a cassette that can be easily removed

Another interesting example is the large-bay photo scanner with a slide-out tray.

Note that the large compartment can also accommodate small devices through the transition frame - "pants".

In addition, only the body of the midi tower can completely block the 17 "" display from the bright side light (the height of the mini tower is not enough for this). Thus, the midi tower is a good compromise between scalability and compactness.

Choose a midi tower

Where to stand midi

In my opinion, the optimal place for a midi tower is on the table, since:

• it can block the 17 "" display from bright side light;
• removable disk drives (floppy disks, etc.) are easily accessible;
• indicator lights are visible;
• the inside of the case is easily accessible;
• less dust is sucked in (which decreases exponentially with height);
• the case is well cooled;
• the length of the peripheral cables is always sufficient.

That is why I am skeptical about the so-called computer tables, similar to whatnots, which negate the indicated advantages (where the tower languishes in a cramped compartment near the floor).

Number of small compartments

In addition to the number of large external compartments (which determine the type of tower), the hull also has the following parameters:

• small (3.5 "") outdoor
• small (3.5 "") internal

Number of small outer compartments usually equal to 1 or 2. One bay is now almost always occupied by a flop drive, since the industry has not been able to move to a larger drive since 1984 (in the sense that there is no industry standard).

The second compartment can, for example, be useful for:

• a high-capacity floppy disk drive (such as Zip or Orb);
• USB port hub. It is convenient when you often need to connect external devices with a USB interface;
• IR transmitter. Used, for example, to work with a printer.

Number of small internal compartments usually also 1 or 2. These are used to install hard drives. For scalability purposes, it is also desirable that there are 2. For example, when capturing video, sometimes an array of 2-4 hard drives.

Choose a midi case with 2 outer and 2 inner small compartments

Power type and case form factor

Type of food

The chassis comes with a built-in power supply (it generates different voltages for internal devices and the motherboard). The following types are used for home computers:

• AT- morally obsolete. Used for low-cost computers
• ATX- newer, which has advantages over AT (see Appendix)

New types of power supply (after AT) are being developed by the company Intel based on the development needs of computers, especially motherboards. At the same time, the transition to lower voltages, the improvement of the mutual arrangement of internal components, as well as the rejection of outdated buses and ports were taken into account.

Understanding the case form factor

In fact, AT and ATX are specifications describing the case-motherboard bundle. They determine not only the type of power supply, but also some design elements and the mutual arrangement of components (for more details, see below about the advantage of ATX over AT).

Comprehensively, this is called the form factor (for short, FF). Therefore, they speak of a case having the ATX form factor (similarly for AT).

Choose the FF ATX midi tower

Case quality

Metal thickness

The main parameter of the quality of the case is the thickness of the metal of its chassis (supporting frame), as well as the walls (casing). If the chassis is made of thick metal, there is virtually no noise or vibration. In addition, such a case is durable, which is also important. If the chassis is solid, then the walls (casing) are the same. On the contrary, in cheap cases, the walls bend easily, like tin :)

Choose a case with a chassis metal thickness of at least 0.8 mm, preferably 1 mm

Smooth chassis

On some models, the edges of the chassis are not machined. Therefore, during installation, if you do not work with a file yourself, you can cut your hand or drive a metal splinter. There are hulls with machined smooth edges and even a painted chassis.

Low radiation outward

A good case should be shielded, i.e. Do not let out radio frequency interference that interferes with external devices and consumer electronics. Radiation is detected, for example, if you approach a computer with a radio receiver with the cover removed - the sound will immediately be covered with crackling and hissing.

The criterion is the presence in the specification of compliance with a strict (American) standard FCC Class B by the amount of radiation from office and home computers. Note that sometimes the term Class B omitted in the documentation.

Also note that the best enclosures are covered from the inside with permalloy- a material that does not transmit low-frequency electromagnetic radiation. True, cases with such a coating cost about 2 times more than conventional ones.

Shielding is carried out due to the tight fit of the walls to the chassis by means of special lugs.

Power Supply

Power

There are several standard power ratings. For a home computer, 200, 235 and 250 W are suitable, and the last two values ​​are characteristic for an ATX case. Note that, despite forecasts of lower power consumption, modern high-speed hard drives and graphics accelerators are more likely to raise the bar. The same applies to magneto-optics. Since it is useful to have a power reserve, then recommended power 235 W .

The suspend to RAM function requires a large current (720 ma, otherwise you cannot power the memory). This current is provided by Elan 10AB (750). Apparently, therefore, high power will not hurt.

Note that the output of the AMD Athlon processor overturned the established ideas about power: the recommended power supply unit for it is at least 300 W.

Power supply quality

The power supply unit is required to consistently produce the required ratings and serve for a long time and reliably. The advanced units also correct (to a greater or lesser extent) deviations in the input power. A striking example is Seasonic SR-250FS-Rx power supplies, which allow very wide variations: 180-264 V in voltage and 47-63 Hz in frequency.

The quality of the PSU largely determines the longevity of the internal components. If the power supply fails, then, firstly, no external power supply devices (filters, stabilizers, etc.) will help. In addition, these failures are difficult to diagnose and you can spend a lot of time checking the main board, memory, etc. until the turn comes to the power supply.

The life of the power supply is 4-7 years, and it can be extended by turning off and on the computer less often, and the interval between successive shutdowns and switching on must be at least 10 seconds. If the power supply fails, it is easier to replace it than to repair it. Power supplies are sold separately, but good power supplies cost $ 35-40 (that's why a good case can't cost $ 40 :)).

The minimum requirements for a power supply are at least one certificate from reputable test laboratories from among: UL, CSA, TUV, CB, CE, VDE, FCC, FTZ, DEMKO, NEMKO, FIMKO & SEMKO (this is specified in the specification for the unit). The corresponding stickers are located in a prominent place on the unit. Usually, sellers' offers are limited to mentioning TUV (which, in principle, is enough).

Choose certified power supplies

Switch or socket?

On the power supply, in addition to the mains plug, there may be either an outlet for powering the display or a switch (the latter is typical for ATX power supplies).

ATX power supplies voltage all the time to the motherboard. If you need to work inside the case, you need to disconnect the power from the computer. A power supply with a switch allows you to quickly and conveniently de-energize the motherboard.

Preference should apparently be given to a switch that provides additional convenience. Then connect the display to a separate socket with its standard cable. When connecting through the body, a socket is saved, but an adapter is needed, so the gain is doubtful. And besides the display, there seems to be nothing more to power :)

By the way, in the case of AT power supply, the use of an outlet is undesirable, since the power button of the computer simultaneously turns on both it and the display. This will burn the breaker as the 17 "" CRT display draws a decent amount of current.

Case functionality

Ease of access inside

Removable side panel (left when viewed from the face) provides easy access to internal components. In some cases, both sides are removed (then, for rigidity, the top wall is usually integral with the chassis). In the traditional version, the casing is U-shaped.

For quick removal (casing or wall), instead of traditional screws, slotted head screws (thumbs) or latches are used. This allows you to do without a screwdriver at all.

In some cases, a sliding frame is also used, on which the plate with the motherboard is located. You do not need to remove everything inserted into the board, including the cards. However, the need to disconnect the indicator wires from the board, as well as turn the case (if it is pushed up against the wall) reduces the attractiveness of this solution.

Here I cannot help but tell you how cool this problem is solved by PowerMac (not to be confused with the "household" iMac, where the case and the display are one whole). There, the right wall can be opened like a secretaire door (that is, the pivot axis is the lower right edge) And together with the wall, the motherboard also rotates, becoming accessible.

Control buttons design

On the front side there are at least 2 buttons: on ( POWER) and reboot ( RESET, reset). Certain requirements are imposed on their design (for example, it is very bad if they are all the same, for example, round, of the same diameter and color, and are located close to each other).

Off button

Power button requirements:

• should stand out in color and size from others
• should not protrude, it is better when it is slightly recessed (this way it is less damaged and more difficult to accidentally press it)

Note that for AT type power the best switch is a toggle switch. For ATX-type power supply, this is basically impossible, since the duration of pressing is also measured here (developed BIOS is programmed to emergency power off when pressed for more than 4 seconds, when the main button does not work)

Reset button

This button should be shallow and recessed to make it difficult to unintentionally press it. The best option is when it is so small that it is pressed only with a thin object such as a ballpoint pen.

Sleep button

Available on some ATX cases. Allows you to instantly send the computer to sleep (power saving mode) if you need to pause in work. A more expensive alternative is to use a keyboard with the same button. This is not to say that this button is vital :)

Power supply location

The tower power supply is usually located at the top of the chassis, and the motherboard is located below it. In sufficiently tall cases, the power supply is located completely above the motherboard, so that their projections on the side wall do not intersect. This is the usual "no overlap" arrangement.

This is especially clear when the unit is on a shelf (there is also a simple screw fixing to the back wall).

In lower cases (39 cm and below), these projections partially intersect, since the power supply is rotated 90 ° relative to the longitudinal axis. Therefore, such cases are somewhat wider than usual ones - about 22 cm. There is a processor socket on the system board under the power supply unit. This creates the following inconveniences:

• the processor is closed by the power supply and therefore, to work with the processor, you must first dismantle the power supply (or work blindly)
• the power supply clutters up the space near the processor, impairing its airflow
• there is a restriction on the height of riser cards for processors (socket version for slot socket). To get around this, ASUS offers special low-profile risers.

Obviously better high hulls, "no overlap"

Case dimensions

Let's repeat that for a home computer, a compact case is not the best option.

The body height must be at least 42 cm. First, it almost guarantees that the PSU is positioned without overlap (see above). But the main thing is that such a case can block the 17-inch display from the side light.

The next requirement is subjective: it is important for me that body depth was no more than 45 cm... The point is that I am holding the mouse on the left side, despite the fact that I am right-handed. I just noticed that the gray and service keys make the hand fly after the mouse a decent tens of centimeters in one "swing". Probably hundreds of meters run in a day :) For the mouse on the left side, this does not happen. The case is moved to the display and therefore the mouse pad is located just opposite the case. Despite the fact that the table has a decent depth - 77 cm - the indicated depth of the cabinet is the limit, given that the table is pushed against the wall, and there should be at least 5 cm behind the cabinet for proper ventilation and so that the cables do not bend too much.

Note that the short ones turned out to be significantly smaller than the long ones (47 cm and more).

The width of the case does not play a special role and the range of 17-20 cm is quite normal. If the body is wider, then you need to check if there is no overlap.

Easy replacement of drives

The point is to replace (remove, insert) drives without removing the plate from the motherboard, but only by removing the walls (or even one wall).

It's all about the right (as viewed from the front side of the case) screws that attach the drive to the frame of the bays, which are covered with a plate (the screws on the left are always accessible).

There are housings where the specified replacement is possible. The following solutions are applied there:

• The box of small compartments is made removable (slides to the left on a slide). In this case, if there is a drive in the box that is inserted into the compartment, then the front panel must also be removed.
• On the plate that carries the motherboard, holes are made opposite the screws, so you can contrive to work with the screws with a screwdriver and tweezers.
• The plate that secures the motherboard is mounted on a frame that slides back on a slide. Then it is enough to move the frame (by pushing the latch) 10-15 cm in order to gain access to the right screws of the drives. The drive cables do not need to be removed. Usually it is not necessary to remove the thin LED wiring, as on most ATX boards they are located in the lower near corner of the board.

Space for a second fan and its size

All good modern cases provide for the possibility of installing an additional fan (the main one is built into the power supply). It is used to cool such "hot" devices as a high-speed disk (7200 rpm and higher), a modern 3D graphics card, and an overclocked processor. Fitting means there is a grill in the chassis and space for screws.

A place for an additional fan is provided either in the front, in the lower part, or in the back, under the power supply.

In the first case, the flow passes through the body, which is optimal for cooling. These models are recognizable by the decorative grilles at the front (through which air is sucked in). However, front suction creates additional noise.

In the second case, the air flow is not optimal, but the additional fan blows the processor precisely. It is also quieter.

Some models provide for both types of installation of additional fans!

Interestingly, according to the upcoming PC "2001 specification (a computer that does not meet this specification, loses the Windows Hardware Quality Laboratory certification, which evaluates whether a component or an entire PC is suitable for Windows. Briefly and clearly.) The noise level emitted from the case, is set at a very low 37 dB, which is much less than 2, let alone 3 fans, so changes are in store for us in this area.

Floppy disk slot

Some housings have a slot-shaped flop tray (see photo). It looks attractive, but you literally have to pluck a floppy disk out of the case (it is not always easy to push it in either).

These cases sometimes have a deeper bezel, so it is also difficult to remove or insert a CD.

IR transmitter window

Some housings have a hole and a receptacle on the inside for mounting the "eye" of an IR (infrared) transmitter, which is typically used for wireless transmission to a printer. Only a small number of buildings have such a window.

Note that an alternative is IR transmitters that are mounted in a small compartment in the housing.

Filter for model selection

Below are ATX midi cases (i.e. with 3 large external bays) available on the Moscow market and meeting the following requirements:

• thick steel
• with certified power supply, power at least 235 W, with controlled fan speed
• without overlapping the system board with the power supply
• with space for an additional fan
• with certificate FCC Class B for radiation
• with smooth finished edges
• with removable side panel
• without slotted flop tray
• no more than 47 cm long

Running a little ahead, I will say that now such models can be bought for $ 60-75. The purchase will weigh about 10 kg. It's not hard, but cumbersome. So, when you go shopping, grab your ropes and a stick. The last one, tucked under the ropes, will be a good handle.

Filter Housing Models

All enclosures are ISO 9002 certified and the power supply has its own switch.

Brand	Aopen HX-45A	Denco Dx08	Hansan Feel 505	InWin S500	LCT LX734A	SIC 62101X
3.5 "" int.
H. cm
Shire. cm
Depth cm
Metal mm.
Add. fan	1 front big		2 large	1 rear big	1 before. and 1 rear.	1 rear big
Access to 3.5 ""		• hole	• hole	• removable	• removable
Off. on PSU
Price $

Aopen

In addition to the HX, the 45 series also includes the HQ, HC, LX, HT models, which differ only in design (however, only the HX-45 is actually being imported so far). The HX-45A has a 250W PSU and the HX-45 235W. Company website: www.aopen.com.tw

The body is made of high quality steel with a thickness of 1 mm. The HQ45 has a power output of 250W and is a new model.

Aopen HX-45A

Denco

The buildings of this company also have a Rostest certificate. There is a button SLEEP... The casing is made of two halves, one of which is L-shaped, so it is more convenient to remove the small wall. It is attached either with two thumbscrews or removed with a handle-lock. On the side inside there is a swivel plate for installing an additional 3.5 "" or 5.25 "" hard drive (mounted on a vertical axis). All Dx08 models share similar characteristics. Company website www.oceanhk.com/denco

Note that the smart buttons RESET and SLEEP made only for D908. Others have them side by side and look the same. You can imagine how much fun it will be when, instead of SLEEP the user inadvertently clicks RESET(apparently, it should be recommended to glue RESET button with scotch tape :)). This is especially true for the D708, where these buttons are so large and so located that they are easy to touch.

Denco D608	Denco D708
Denco D808	Denco D908

On sale there are mainly cases with an Oktek X20 235 W power supply and, less often, SeaSonic 250 W (the latter in modifications with an outlet or a switch). Cover plates for cards are removable.

Hansan Systems

A feature of Hansan Systems' cases is thick steel - 1 mm (1.2 mm for some parts). Company website www.hansansystems.com

The control buttons for the considered model Feel 505, although they have the same size, different colors. The indicators are located above and covered with dark plastic (which gives the case a certain elegance).

Feel 505

Feel 505 from the inside

On the company's website there is an even shorter Feel 501 model with a depth of 42 cm.

In addition to this model, modifications with various "muzzles" are widely represented, all are very nice, but long (due to the excessively deep front panel) and with a slit :(

The sellers do not have the manufacturer's name and the models are represented only by names.

InWin

All models have low noise power supplies and a separate switch. Models are sometimes called by sellers Solist... The plastic components are UL certified for impermeability. Company website www.in-win.com

The InWin S500 is made of Japanese steel and has two removable side panels. Bays for 5- and 3-inch drives slide out on a skid to the left; it is possible to install two additional fans. As you can see, the disadvantage is somewhat greater depth.

There are also models of the A and Q series (A500, A700 ...). They have a U-shaped casing, but steel is 1 mm, and galvanized.

InWin S500

LCT Technology

LCT Technology is YueSovskaya, so there is reason to believe that the hulls are well designed :). And they are made in China, which ensures low prices. The website of the company is www.lct-tech.com There is a representative office in Moscow, which ensures the supply of many models.

Particularly interesting is the LX 734A model:

• 1mm steel is used
• the bezel can be easily detached (no screws), giving access to devices in the compartments (see below)
• all drives in the bays each have their own sleds (the latter are included in the housing kit). After removing the muzzle, you can take out any device in the compartment forward (by pressing the latch)
• boxes are removed
• both walls are removed (one screw with a head, although you must first remove the "" muzzle "")
• compartments closed with break-out plates
• The package includes an additional front cooler (80 mm.)

And all this for a reasonable price.

Of the cheaper models (made of thinner steel), we note the TSK-T081.

SIC

Korean manufacturer. The company site could not be calculated (hence the data gaps). Externally, the cases make a good impression. All models have 250W certified power supplies.

SIC62101X

There are also a large number of unusual-looking models, for example, with the bottom arrangement of large compartments and a power supply unit.

Application: Other enclosures

CAT

The manufacturer and his website are unknown. The models are quite cheap, but there are no ones that pass through the exposed filter.

Elan vital

It is a subsidiary of the famous ASUS. Company website: www.elanvital.com.tw Of the two models available on the market, the T-10AB with 1 small outer compartment is of interest. It occupies some intermediate position between midi and full towers. The second model, the T-5AB, has a motherboard overlap.

The power button stands out from the reset button in color and design and is fixed by turning it 90? (so it is impossible to accidentally turn off the computer). The body is installed on flat legs, which can protrude or not protrude beyond the projection of the body by turning. The 3- and 5-boxes slide out to the side on a slide. The indicators are located on the top edge and are visible even when standing on the floor. Both side walls are removed, using thumbscrews that remain in the walls (so that they cannot be lost). The cables from the buttons and LEDs pass in special boxes and are fixed. Button RESET recessed and made very small.

Note that all Elan Vital cases have not only a window for the IR transmitter (in the photo it is under the button), but also a socket for it.

Enlight

A well-known manufacturer of inexpensive cases from Hong Kong. It is also interesting in that it also produces power supplies. The company's website is www.enlightcorp.com Unfortunately, the company does not seem to have models that pass through the exposed filter (or with the power supply overlapping the motherboard, or there is no required number of bays). However, there is the EN-7230 series with 4 large compartments, 48 ​​cm high.

FKI

Unfortunately, the FK-505 model, passing through the filter, has not been imported yet. Instead, importers prefer the 600 series models, which have a killer depth of 48.5 cm (for which the price is indicated). Company website www.fkusa.com

Note that sellers often pass FKI products as Asus (because of the inscription on the front panel), and sellers do not seem to know the name of Fong Kai Industrial :)

Models 505 and have a stand, and the 600 series has legs. The cover plates of the cards break off.

Palo alto

A new player in the domestic market. The company's website is www.paloaltoproducts.com Only the complete PA-810 tower with a height of 48 cm has the required number of compartments.

Application: Advantages of ATX over AT

ATX stands for AT eXtension(AT extension) and is an Intel chassis and motherboard specification (the specification is in multiple editions). Benefits over AT are discussed in more detail below.

Expanding the capabilities of the power supply

The components on the motherboard use both 5V and 3.3V. The AT standard only supplies 5V to the board, while 3.3V is obtained from the voltage converter on that board. In ATX, the 3.3 V voltage is generated by the power supply itself, so there is no need for a converter on the board. This frees up space on the board and improves thermal performance.

For flexible control of "sleep" modes with the ability to "wake up" from the keyboard, call a modem and other events, a constant voltage supply to the system board is provided. If the chassis is made to full specification, the power supply has a separate switch on the back of the chassis to de-energize the system board.

Optionally, fan speed control, temperature control of the power supply and voltage control of 3.3 volts are possible.

Air flow direction

In an AT chassis, the PSU fan always blows air (from the back). The original ATX specification called for air intake to direct air flow to the processor. This allows you to completely abandon your own cooler on the processor, replacing it with a large heatsink. Now it's no big deal if the silent cooler suddenly fails and the processor overheats and breaks down. I have seen this solution in desktop cases from Compaq.

This solution is really good for desktops. It turned out to be more convenient for the towers to still blow out air, which improves heat transfer. The fact is that, firstly, the power supply itself heats the air, and secondly, the warm air rises upward. Further, the power supply itself is conveniently placed above the motherboard and even on a shelf. So it no longer blows the motherboard. And as we know, an additional fan is used to blow the processor around.

Port connectors are located on the main board

The port connectors facing the rear of the chassis are located on the main board itself. For AT boards, they are located on brackets to which the connecting cables lead. As a result, ventilation of the board is improved and installation is simplified.

On this basis, it is easy to distinguish ATX from AT: at the rear, the connectors in the tower case are located not in horizontal rows, but in vertical rows (in the Desktop - vice versa).

Reducing the length of the connecting cables

The IDE ports are located on the motherboard closer to the drive bays for shorter connection cables and better ventilation. Moreover, it makes it easier to access the processor and memory modules. By the way, reducing the length of the cables is important for the stability of the operation, because The IDE interface is sensitive to interference.

Further, unlike AT, where the motherboard is attached to the case with plastic legs, ATX uses screws, which adds reliability (however, this is ideally - in practice, motherboards in ATX cases are often fastened with plastic legs).

Application: Changing the case

Note that many housings are shipped with 1-2 missing front and rear plugs. Do not be intimidated by this - it was conceived to reduce the cost.

In the case of AT power supply, the new power supply can be checked by connecting only a hard disk or a CD drive to it and make sure that they spin up, and the CD indicator light is still on (connecting the floppy drive will do nothing, since its indicator glows only during operation with a floppy disk).

An ATX power supply needs a ready signal from the motherboard, otherwise it simply won't start. Therefore, the power supply must be deceived, for which:

1. In the off state, carefully close the "Power Supply On" contact (pin number 14, usually green) in the connector of the connector inserted into the motherboard with any "Ground" contact (pin numbers 3, 5, 7, 13, 15-17; they can be black, gray, or brown). Note that the pins are described in the motherboard manual
2. Connect a load in the form of a hard disk or CD drive
3. Switch on the power supply. Its fan should rotate, and the connected drive should also spin.

Replacing or installing a new chassis consists of the following steps (using the documentation for the motherboard):

1. Opening the case
2. Installation of actuators The case comes with a package of screws. There are two types of screws with slightly different diameters. The smaller ones have a round head and are designed for CD and floppy drives. The large ones are for hard drives and everything else and have a hexagonal head. Power is connected to the drives. The power connector for the floppy drive is small and flat
3. Installation on system board processor, memory, graphics card... It is clear that it is more convenient to insert a processor onto an "open" board. As for the graphics card and, especially, memory modules, they are forcefully inserted into the new board. If the board is attached to the plate, then it is like a canopy, bends and crunches. Not all boards can withstand this kind of flex. The board can be placed on the table with a mouse mat under the desired slot, or placed on an edge and supported on the other side with your hand
4. Securing the system board to the plate The position of the board is determined by the fact that its bottom and outer edges must closely adjoin the corresponding edges of the plate. Legs are attached to the plate in appropriate places. ATX-boards are fixed with screws on screw-in feet (AT-boards are fixed on plastic feet), and insulating washers are placed under the screws. The upper right corner of the board is fixed on the leg - "cufflink"
5. Fastening the plate with the board to the case
6. Connecting the interface cables to the board The floppy drive is connected with an end connector (then it is visible under the name A :). The power cable is connected to the board
7. Connection to the motherboard wires to indicators and switches(they are inscribed). It should be noted here that the green indicator must be connected to the contacts intended for blocking the keyboard (which is confusing, since this is usually not indicated in the documentation for the motherboard)
8. Connection external devices(keyboard, mouse, display)
9. Turning on the computer and checking it is working

Glossary

Micro ATX- case form factor. It is a micro tower with SFX power type. This small chassis contains only a Micro ATX board (has few slots)

SFX(Small Form factor - small form factor) - type of food. It is a modification of ATX for computers with a reduced size with a micro tower case. The main difference is lower power. According to the SFX specification (included in the Micro ATX specification), the total power of the supplied devices should not exceed 90 VA. Used in office computers. SFX does not support the -5 volt voltage that powers ISA cards (see the boards chapter) and which should not be available on Micro ATX boards

Slim- types of desktop type cases, only very flat. Used for office computers. The motherboard must be in NLX form factor (or LPX in the case of AT power supply) to fit in such a case.

In contact with

classmates

The form factor of computer cases and motherboards is one of their significant characteristics. Often they are faced with a misunderstanding of the difference between ATX and mATX, either when assembling a new system, or when upgrading an old one. Most are only familiar with these abbreviations, although there are others in the context. Both standards are similar to each other, and they impose identical requirements for a number of characteristics of a number of components, so ATX and mATX should be considered in relation to motherboards - the form factor will be decisive here.

Definition

ATX- the form factor of full-size motherboards for desktop computers, which determines the dimensions, the number of ports and connectors, and other characteristics. It is also the form factor of personal desktop computers, which determines the size of the case, the location of the mounts, the placement, size and electrical characteristics of the power supply.

mATX- the form factor of motherboards with reduced dimensions and with a cut back on the number of ports and interfaces. Also - the form factor of the case of the system units.

Comparison

The difference between ATX and mATX is primarily in size. Full-size motherboards are installed in full-tower and midi-tower cases, while mATX motherboards are also installed in mini-towers. The standard dimensions of ATX boards are 305x244 mm, although they can be slightly smaller - up to 170 mm. The standard dimensions of mATX motherboards (often called micro-ATX) are 244x244 mm, but they can be cut down to 170 mm. The standards are not very strict, and the difference of a few mm from this or that manufacturer is a common thing and does not affect anything. But the places for the mounts are rigidly standardized by the form factor, and absolutely always coincide with the case holes for installing motherboards. It is visually defined as follows: the first vertical row of holes from the plug is universal, the second is for mATX, the third is for ATX boards. You won't be able to install an ATX board in small mATX cases; on the contrary, in the vast majority of cases, installation will not cause any difficulties.

Another difference is in the number of ports and interfaces. This is not subject to standardization and remains at the discretion of the manufacturer, however, the minimum gentleman's set is predominantly soldered on mATX boards: two, not four, as in ATX, slots for RAM, fewer SATA and USB interfaces, one video output is displayed on the rear panel (if yes), input-output ports, often combined, at least USB, most often there are no excesses like eSATA or HDMI. All motherboards today are equipped with an ethernet port. The number of PCI slots on mATX boards is minimal, so installing a video card plus a couple of expansion cards is the ultimate dream. Also, due to the reduction in area on small boards, integration is always relevant, plus the number of soldered parts is less.

In practice, a computer user will hardly find any differences between the form factors of motherboards. Due to the small size of the enclosures and the "accuracy" of the mATX electronics, it can get hotter, and the installation of new components can be inconvenient due to the saved space.

Conclusions site

1. ATX is more of both a motherboard form factor and a case form factor.
2. mATX has reduced functionality due to the reduction in the number of ports and connectors.
3. MATX cards can be installed in ATX chassis, and not vice versa.
4. In some cases, mATX is inconvenient when installing accessories.

Updated 03.11.2013 23:29

Hello everyone! Today we will talk about an ATX power supply.

The choice of a power supply unit for a personal computer should be approached with special responsibility, since the stability and reliability of the operation of the entire computer as a whole largely depends on it. This article describes the design features of the power supply unit, characteristics ... Read more ...

The power supply is an integral part of every computer. The functioning of the entire personal computer (PC) depends on its normal operation. But at the same time, power supplies are rarely bought, since once a good power supply is purchased, it can provide several generations of continuously evolving systems. Considering all this, the choice of a power supply unit must be taken very seriously.

The power supply generates voltages to power all PC functional units. It generates the main supply voltages for computer components: +12 V, +5 V and 3.3 V. The power supply unit also generates additional voltages: -12 V and -5 V and, in addition, it provides galvanic isolation from the 220 V.

Internal design of the ATX PSU

The figure (Fig. 1) shows the internal structure and arrangement of elements of a typical power supply unit with an active power factor corrector (ACKM) "GlacialPower GP-AL650AA". On the power supply board, the numbers indicate the following elements:

1. Current protection control module;
   
2. Filter choke for +12 V and +5 V output voltages, which also performs the function of group stabilization;
3. Filter choke +3.3 V;
4. Radiator with output voltage rectifier diodes;
5. Main converter transformer;
6. Key control transformer for the main converter;
7. Transformer that forms the standby voltage of the auxiliary converter;
8. Power factor correction controller (separate board);
9. Radiator with diodes and keys of the main converter;
10. Mains voltage filter;
11. KKM choke;
12. Line voltage filter capacitor.

This design of ATX power supplies is the most common and is used in power supplies of various capacities.

ATX PSU connector types

On the back of the power supply unit there is a socket for connecting a network cable and a mains switch. In some models of power supplies, the mains switch is not installed. Sometimes, in older models, you can find a connector for connecting a monitor's network cable next to the network connector. In modern power supplies, on the rear panel, manufacturers can install the following connectors (Fig. 2):

• Mains voltage indicator;
• Fan control button;
• Button for manual switching of input voltage (110 V / 220 V);
• USB ports built into the PSU.
  

In modern models, an exhaust fan is rarely installed on the back wall. It now sits on top of the PSU. This allows a large and quiet cooling element to be installed. On power supplies with increased power, such as the Chieftec CFT-1000G-DF power supply, two fans are installed on the top and on the back cover (Fig. 3).

A wiring harness with connectors for connecting the motherboard, hard drives, video card and other components of the system unit comes out of the front wall of the power supply.

In a modular-type power supply unit, instead of a wiring harness, on the front wall there are connectors for connecting wires with different output connectors. This allows you to streamline the supply wires in the system unit and connect only those that are necessary for this configuration (Fig. 9 and 10).

The pinout of the power supply output connectors connected to the motherboard and other devices is shown in the figure (Fig. 4).

It should be noted that the colors of the wires are unified, and each color corresponds to its own voltage:

• Black - common bus (Ground);
• Yellow - +12 V;
• Red - +5 V;
• Orange - +3.3 V.
  

The figure (Fig. 5) shows the output connectors of the ATX power supplies.

Not shown in the figures (Fig. 4 and 5) connectors for additional power supply of video cards, their pinout and appearance are similar to the pinout for connectors for additional power supply of the processor.

Electrical parameters and characteristics of PSU

Modern power supplies for PCs have a large number of electrical parameters, some of them are not marked in the "technical specifications", since they are considered not important for the user. The main parameters are indicated by the manufacturer on a sticker located on the side wall.

Power supply power

Power - this is one of the main parameters of the power supply unit. It characterizes how much electrical energy the power supply unit can give to the devices connected to it (hard drive, motherboard with a processor, video card, etc.). To select a power supply unit, it would seem that it is enough to sum up the consumption of all components and choose a power supply unit with a small power reserve.

But things are much more complicated. The power supply generates various voltages distributed over different power buses (12 V, 5 V, 3.3 V and others), each bus (line) voltage is designed for a certain power. One would think that these powers are fixed, and their sum is equal to the output power of the power supply itself. But in the ATX power supplies, one transformer is installed to generate all these voltages, so the power on the lines floats. When the load on one of the lines increases, the power on the other lines decreases and vice versa.

The manufacturer in the passport indicates the maximum power of each line, summing them up, the power will turn out to be more than the power supply can actually provide. Thus, often, the manufacturer declares the nominal power that the PSU is unable to provide, thereby misleading users. An insufficient power supply unit installed in the system unit causes "freezes", arbitrary reboots, clicking and cracking of the hard disk heads, and other incorrect operation of devices.

Permissible maximum line current

This is one of the most important parameters of the power supply, but when purchasing a power supply, users often do not pay due attention to this parameter. But when the line current is exceeded, the power supply turns off (protection is triggered). You will need to disconnect it from the 220 V network and wait about a minute. It should be borne in mind that the most powerful consumers - the processor and the video card are powered by a 12 V line, therefore, when buying a power supply unit, you need to pay attention to the values ​​of the currents indicated for it. To reduce the current load on the power connectors, the 12 V line is divided into two parallel ones (sometimes more) and denoted as + 12V1 and + 12V2. When counting, the currents on the parallel lines are summed up.

For high-quality power supplies, information on the maximum current loads along the lines is indicated on the side sticker in the form of a plate (Fig. 6).

If such information is not indicated, then one can doubt the quality of this PSU and the correspondence of the real and declared power.

Operating voltage range

This characteristic means the range of the mains voltage at which the power supply unit will remain operational. Modern power supplies are available with ACKM (active power factor corrector), which allows you to use the input voltage range from 110 V to 230 V. But inexpensive power supplies with a small operating voltage range from 220 V to 240 V are also produced (for example, FPS FPS400-60THN- P). As a result, such a power supply will turn off when the mains voltage drops, which is not uncommon for our power grids, or even will not start at all.

Internal resistance

Differential internal resistance (electrical impedance) characterizes the power supply losses during the flow of alternating current. To combat it, a low-pass filter is included in the power supply circuit. But it is only possible to significantly reduce the impedance by installing large capacitors with low series resistance (ESR) and chokes wound with a thick wire. It is quite difficult to implement this constructively and physically.

Output voltage ripple

A personal computer power supply is a converter that converts AC voltage to DC voltage. As a result of such transformations, there are ripples at the output of the power lines (impulse change in the voltage value). The problem with ripple is that, if filtering is insufficient, it can distort the performance of the entire system, lead to false switching of comparators and misperception of input information. This, in turn, leads to errors in operation and disconnection of PC devices.

To combat ripple, LC filters are included in the circuit of the output voltage lines, which smooth out the ripple of the output voltages as much as possible (Fig. 8).

Stability of voltages

During the operation of the power supply unit, its output voltages change. An increase in voltages causes an increase in quiescent currents, which in turn causes an increase in dissipated power and overheating of circuit elements connected to the power supply unit. A decrease in the output voltage leads to a deterioration in the operation of the circuits, and when it decreases to a certain level, the PC elements stop working. Computer hard drives are especially sensitive to voltage drops.

The permissible voltage deviations of the output lines for the ATX standard should not exceed ± 5% of the nominal line voltage.

Efficiency

The efficiency of the power supply determines how much useful energy the system unit will receive from the energy consumed by the power supply. Most modern power supplies have an efficiency of at least 80%. And the power supplies equipped with PKKM (PPFC) and AKKM (APFC) significantly exceed this figure.

Power factor

This is a parameter that you should pay attention to when choosing a power supply, it directly affects the efficiency of the power supply. With a low power factor, the efficiency will also be small. Therefore, automatic power factor correctors (ACKM) are built into the circuits of modern power supplies, which significantly improve the characteristics of the power supply.

The first step when choosing a power supply should be determined with its power. To determine the required power, it is enough to sum up the power of all components of the system unit. But sometimes individual video cards have special requirements for the current on the +12 line. B, this must be taken into account when choosing. Usually, for an average system unit equipped with one video card, a power supply unit of 500-600 watts is enough.

When choosing a model and a manufacturer's firm, you should read the reviews and reviews on this PSU model. It is advisable to choose a power supply unit with an ACKM circuit (APFC). In other words, you need to choose a power supply so that it is powerful, quiet, high-quality and meets the declared characteristics. Saving a dozen or two dollars is not worth it. It must be remembered that the stability, durability and reliability of the entire computer as a whole largely depend on the operation of the power supply..

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