The process of assembling a new stationary computer or upgrading an old one is always accompanied by not some questions, the answers to which need to be received timely – before the purchase of expensive components.

Therefore, at the planning stage of the PC configuration, the user, first of all, must determine for himself which form factor of the motherboard will be applied in it. “But what is a form factor of a motherboard, dammit?!” – an understandable question, I’ll get to that… right now!

In this article I will consider:

  • What is a form factor of a motherboard?;
  • Why it is so important?
  • Types, formats, sizes, and purpose of different form factors.

What is a motherboard form factor?
Why it is so important?

The motherboard form factor is a standard set by the manufacturers, which specifies its overall and connecting dimensions, that is, the size of the mount to the case, the number and location of the interface slots for connecting RAM, video card, various expansion cards, input and output ports and other necessary interface connectors.

As you can see, this parameter directly affects both the appearance of the whole assembled system unit and its hardware stuffing.

After all, the form factor of a motherboard sets a bunch of parameters for the future assembly, starting with the size of the case of the computer system unit, ending with the type of cooling system built into it!

If you will choose the wrong form factor of the motherboard, the consequences can be sad, leading to unplanned expenditure of the budget.

You need to take into account many factors:

  • the size of the case of the system unit
  • its internal space for installing:
    • expansion cards (audio cards and network adapters);
    • video cards;
    • processors;
    • power supply;
    • disk system;
    • cooling system.

If the configuration is designed for a powerful gaming computer, then most of the listed items require special attention.

The review of classifications of motherboards will begin with the most popular form factors in the circles of ordinary users and ending with professional-level motherboards designed for special tasks.

Form Factors for Office and Gaming PC Boards

ATX Form Factor (highly recommended for most PCs)

This format is the most popular for the construction of stationary computers of any configuration, ranging from the office version to the powerful gaming station. ATX format motherboards have standard sizes of 30.5 x 24.2 cm, which allows manufacturers to easily provide them with all the necessary functionality and a complete base – slots, ports, interface connectors, reinforced power circuits, etc.

The important design features of this motherboard size should be attributed to the fact that they are compatible only with housings of system units of the same ATX standard. On the one hand, this would seem to be a minus, but on the other hand, assembling computers with their use can save the user money from the budget allocated to them.

First, the computer assembled on their base is less demanding of the cooling system, because the components of its hardware filling do not have to huddle in a small case, which means they have good ventilation without the use of expensive cooling systems.

Secondly, the segment of cases compatible with ATX motherboards is larger compared to other sizes. Therefore, assembling a computer, the user will have no difficulty in choosing the casing of the future PC either on the financial side of the issue or on the choice of model.

MicroATX (mATX) – Good for compact PC builds (and also for budget options)

The microATX motherboard form factor was presented by Intel in December 1997 as a variant of the reduced ATX board designed for small and low-cost systems.

Reducing the form factor of the ATX standard board led to a reduction in the size of the case, the system board, and the power supply and, ultimately, the cost of the entire system. In addition, the microATX form factor is compatible with ATX, which makes it possible to use the microATX motherboard in a full-size ATX package.

But you cannot insert a full-size ATX motherboard into the microATX chassis, as you understand. Currently, mini-tower systems dominate the market for cheap PCs, despite the fact that their small size and narrow case seriously limit the possible upgrades.

The microATX and ATX form factors (or mini-ATX) motherboards have the following major differences:

  • reduced size: 244 x 244 mm (9.6 x 9.6 inches)  instead of 305 x 284 mm (12 x 11.2  inches)  for ATX and instead of 284 × 208 mm (11.2 × 8.2 inches) for mini-ATXComparison ATX-microATX-miniATX

Dimensions of ATX, mini-ATX, and microATX

  • reduced number of expansion slots (maximum four, although in most cases only three);
  • reduced power supply (supply form factor SFX / TFX).

The maximum dimensions of the microATX motherboard are only 9.6 × 9.6 inches (244 × 244 mm) compared to the dimensions of a full-size ATX board (12 × 9.6 inches, or 305 × 244 mm) or mini-ATX (11.2 × 8.2 inches, or 284 × 208 mm). The dimensions of the motherboard can be reduced if the location of its mounting holes and connectors is in accordance with industry standard.

The reduced number of connectors is not a problem for the average user of a home or office computer, since a number of system components, such as sound and graphics cards, are often integrated into the motherboard. High integration of components reduces the cost of the motherboard and, accordingly, the entire system. External USB connectors, 10/100 Ethernet, sometimes SCSI or 1394 (FireWire) may also contain additional expansion slots.

In microATX systems, by matching the connectors, the standard ATX power supply was used successfully.

But despite this, especially for such systems, a reduced power supply form factor, called SFX / TFX, was developed.

Reducing the size of the power supply allows you to improve the layout of the elements and, accordingly, reduce the overall size of the system and its power consumption.

But when using the SFX / TFX power supply, you may encounter a lack of output power for faster or fully configured systems. Since modern computers consume a lot of electricity, most third-party microATX motherboards support standard ATX power supplies, although microATX systems supplied by Compaq, HP, eMachines, and others use some type of SFX or TFX power supply to reduce the cost of a computer.

Compatibility of microATX boards with ATX means the following:

  • usage of the same 20-pin power connector;
  • standard location of I / O connectors;
  • the same location of the mounting screws.

The similarity of the geometric parameters allows the microATX motherboard to be installed in both the ATX chassis, which contains the standard power supply unit and the smaller microATX chassis, using the smaller SFX / TFX power supply unit.

FlexATX – Really small one!

The form factor FlexATX is the next evolution in the direction of reducing motherboards and cheaper computers assembled on their base. Motherboards of this format have a size of 22.9 x 19.1 cm and are intended only for office PCs.

Comparison of ATX, microATX and FlexATX

Dimensions of ATX, microATX, and FlexATX

They, like their predecessors, are fully compatible with the shells of the ATX format system units and with their power supply system.

An important distinguishing feature of the motherboard of this standard, which allows them to reach a low sales value, is their more meager complete base. In some cases, they are not even equipped with expansion slots, and the user has to be content with only USB and IEEE-1394 / FireWire ports.

Special motherboard formats:

Extended ATX (eATX)
(highly recommended for enthusiast PCs)

The dimensions of the form factor eATX are 30.5 × 33.0 cm.

Comparison of ATX, eATX and microATX

Yep, that thing is VERY HUGE

This standard is more applicable to the creation of servers, where the installation of two or more processors, a large amount of RAM and various expansion cards are required on the motherboard.

But also it perfectly suitable for ultra-powerful gaming PCs and workstations!
And furthermore, most of the top hi-end motherboards for the sockets like AMD TR4, Intel LGA 2066, Intel LGA 2011 are already by default is eATX!

If you want to build a really-powerful-mighty-beast-gaming-PC, that is a perfect base to start:

  • a lot of slots for RAM, video cards, HDDs and SSDs;
  • one of the best natural cooling properties in motherboards (because of large space between components)
  • a lot of space for your customization!

In the end…

As you can see, you can build a computer of almost any size thanks to the advancement of form factor technologies – be it small portable office machine or huge, powerful gaming PC/server/workstation!

Today you don’t need to worry so much about form factors of PCs as in old times, because there is a whole bunch of useful standards that allow manufacturers of motherboards to build easily 100%-compatible systems.

You just need a little caution to ensure compatibility of your future system.

And that is freaking awesome! Now everyone can easily build PCs without a headache! It was so frustrating at times!

I hope that you, my dear reader, enjoyed this article and that it was very helpful to you. If you have any questions or don’t understand something in this article, leave them in the comments under that article.

And if you enjoyed this article, you can leave your opinion in the comments too – every opinion of my readers is very important to me.

I wish you all the best and remember:

Computer technology is not rocket science!

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