Motherboard Sizes Guide

Motherboard Sizes Guide

If you are looking for a new motherboard, one of the most important factors is the form factor. In other words, you have to check if the motherboard you want to get is the right size for your case. Sure, bigger motherboards are always better, but do you really need an ATX board for a budget gaming computer?

This motherboard sizes guide is all you need to pick your next motherboard. You will learn everything there is to know about Mini ITX, Micro ATX, ATX, Extended ATX, and XL ATX motherboards. There are some reasons why you might want one over the other and this motherboard sizes guide is going to help you figure it out. Let’s get started!

Mini ITX

The Mini ITX form factor is the smallest of the bunch. It is the perfect choice for a tiny computer that can sit on pretty much any desk, but it is even more popular as a living room computer. If you are buying a Mini ITX motherboard, then you probably have already picked a case that will fit perfectly under your TV, just like a console.

But you still need to take a look at a motherboard sizes guide to learn more about the Mini ITX form factor. They might not be the most popular, but they are pretty much your only choice when it comes to making a tiny computer. Even a Micro ATX board is significantly larger than a Mini ITX one.

Here are the typical specs of a Mini ITX motherboard:

  • Dimensions: 17 x 17 cm (6.7 x 6.7 in)
  • Number of RAM slots: 2
  • Expansion slots: 1
  • Graphics Card slots: 0 to 1
  • SATA ports: 2 to 6

If you are getting a processor with decent integrated graphics, such as an AMD Ryzen APU, then you don’t have to worry if it has a graphics card slot. But if you are building a tiny workstation or gaming computer, pay close attention to the specs to make sure that it supports PCIe x16 for graphics cards.

There are some obvious compromises that you have to make when getting a Mini ITX board. You will have to pay close attention to all the features that a Mini ITX motherboard has, such as M.2 or Wi-Fi, to make sure that you are not making a sacrifice that will turn into a mistake later on.

Also, make sure that you get enough RAM from the get-go because you won’t have any slots to expand it later on. Virtually all Mini ITX motherboards come with only two slots, so bear that in mind.

All in all, it’s great that Mini ITX motherboards exist because they make tiny computers possible. If you always wanted to build a computer but needed something that you can easily carry around the house, then a Mini ITX motherboard is a great choice.

Micro ATX

The Micro ATX form factor, together with ATX, is the most common one. It strikes a good balance between features, size, and price. If you are getting a Micro ATX motherboard, it only makes sense to go with a mid-tower case, but you can also get a full tower if you want more space for futureproofing.

Micro ATX motherboards do allow for multi-GPU setups, but it is not advisable. You would need a PCIe extension cable just to make it work and it still may not be ideal.

On a side note, Micro ATX motherboards tend to be the cheapest form factor available. This is because Mini ITX motherboards are a bit harder to manufacture due to their tiny size and limited space and larger boards have more components and features.

If you wonder what the specs of a standard Micro ATX motherboard are, this motherboard sizes guide is here to tell you:

  • Dimensions: 24.4 x 24.4 cm (9.6 x 9.6 in)
  • Number of RAM slots: 2 to 4
  • RAM Type: DIMM
  • Expansion slots: 2 to 4
  • Graphics Card slots: 1 to 3
  • SATA ports: 4 to 8

If you plan to overclock on a Micro ATX motherboard, it is definitely possible. However, you should get a mid or high-end motherboard that supports overclocking and has good VRMs

Unlike with Mini ITX motherboards, you won’t really make many compromises when you buy a Micro ATX board over an ATX one. If you are like most people and only plan to get a CPU, GPU, two sticks of RAM, an M.2 SSD, a few HDDs, and maybe a few additional case fans, then Micro ATX is a great choice. Pay attention to the number of fan headers, though!


The ATX form factor, also called Standard ATX, is the one that most people get. It is significantly longer than Micro ATX, but it is the same in width. This is because it has more expansion slots and it sometimes even has more than 4 DIMM slots for RAM.

If you want to get a few expansion cards and are worried that you won’t be able to fit all of them on a Micro ATX motherboard, then the ATX form factor is for you. Moreover, ATX motherboards tend to have better support for water cooling, RGB, overclocking, cooling, and so on.

It is common to see three or four fan headers in addition to the CPU fan header on ATX motherboards, so that alone may swing you towards getting it.

Here are the specs that are typical on ATX motherboards:

  • Dimensions: 30.5 x 24.4 cm (12 x 9.6 in)
  • Number of RAM slots: 2 to 8
  • RAM Type: DIMM
  • Expansion slots: 4 to 7
  • Graphics Card slots: 1 to 4
  • SATA ports: 4 to 12

As you can see, ATX motherboards sometimes come with up to 8 RAM slots. But then again, very few people populate more than four slots in the first place, so keep that in mind.

You should really get an ATX motherboard only if you plan to do something with the great number of expansion slots, SATA ports, graphics card slots, and so on. Also, ATX motherboards tend to have a significantly better I/O and more features in the first place over Micro ATX motherboards, and that alone can affect your choice.

Extended ATX

Extended ATX, also known as EATX, motherboards are even bigger than ATX motherboards. This makes them better at dissipating heat and easier to work with when you compare them to smaller form factors. The exact number and type of expandability that you can expect from an EATX motherboard vary a lot, depending on which one you are getting.

In general, EATX motherboards have more (and different) expansion slots when compared to ATX boards. They are 30.5 x 26.9 cm (12 x 10.6 in), which means that they are slightly longer than ATX. You generally get all the same features that you would get with an equivalent ATX motherboard so that alone is not enough to make EATX worth considering.

Extended ATX motherboards have more fan and water cooling pump headers and they also often have more SATA ports as well as M.2 slots. Even if you can get 8 SATA ports and 4 M.2 slots, perhaps the size alone will make it too hard to work with and the slight increase in cost would make EATX a better choice.

So, unless you plan to build a huge computer with many different components, there is little reason to buy an EATX motherboard. Just save the money and invest it into getting a better CPU, GPU, more storage, more fans, and so on.


Last but not least in this motherboard sizes guide are XL ATX motherboards. These are 32.5 x 27.5 cm (12.8 x 10.8 in), so they are even wider and longer than EATX motherboards. Just getting a computer case that can fit such a huge motherboard is a challenge.

XL ATX motherboards are usually combined with the most powerful workstation CPUs on the market, such as the AMD Ryzen Threadripper. These boards are usually very expensive but also full of features.

10 Gbps LAN, Bluetooth, Dual-Band Wi-Fi, USB Type-C, USB 3.2, and so on are all pretty much expected with XL ATX motherboards. Nonetheless, double-check the specifications on the manufacturer’s website to check if it has all the features you are looking for.

Naturally, XL ATX motherboards have even more SATA ports and M.2 slots than smaller form factors, so it’s great if you have a lot of storage devices. Pretty much all of them come with 8 RAM slots and great VRMs for overclocking.

Since these motherboards have to work hard with their powerful CPUs, they often come with excellent heatsinks and even chipset fans. If you are planning to get an XL ATX motherboard, then make sure that you get a huge computer case and a lot of case fans because you will need it. Since these motherboards are very expensive, only true professionals buy them.

What Motherboard Form Factor Should I Get?

Now that you have gone through the motherboard sizes guide and know all the different form factors, which one should you buy? Most people will be happy with either a Micro ATX or ATX motherboard. If you want to have more space and plan to get a second graphics card or add a few extension cards, get an ATX motherboard.

Otherwise, a decent Micro ATX motherboard will do just fine. Another potential advantage that Micro ATX has is that it can fit into smaller cases. Still, if you plan to build the smallest computer possible, you will need a Mini ITX motherboard. You can check this motherboard sizes guide to make sure that you can live with the downsides of a Mini ITX build.

But what about EATX? These motherboards are quite large, so they are not for everyone. EATX motherboards are great if you want to have 10 HDDs, four M.2 NVMe SSDs, 128 GB of RAM, and so on.

But if you don’t plan to spend more money on your computer than on your car, you won’t really need an EATX motherboard. It is great for professionals that need a lot of expansion slots.

And when it comes to XL ATX, those are the largest standard motherboards on the market. XL ATX motherboards only make sense if you need a powerful workstation PC with an AMD Ryzen Threadripper or Intel Xeon CPU. They allow for great expandability and come with great VRMs and cooling all over the motherboard.

While they look great and are packed with features, they are only for professionals that are ready to spend $500 on a motherboard. This motherboard sizes guide did not focus too much on XL ATX motherboards because it is such a tiny market.


Motherboards come in many different sizes and it is important to know the differences. But bear in mind that not all motherboards are created equal and there are huge differences in expandability and features even between two ATX motherboards. This motherboard sizes guide serves only as an introduction to all these different sizes.

If you are building your first computer, go with either a Micro ATX or ATX motherboard because they tend to have great expandability without many sacrifices. Focus on the features that you are interested in, such as Bluetooth and Wi-Fi. You may have to pay more for a smaller motherboard just to get those features, so it is up to you to decide if they are worth the extra cost.

And if you are in the market for an SFF (small form factor) build, a Mini ITX motherboard is your only choice. But remember that these motherboards both cost more and have significantly fewer features and less expandability when compared against Micro ATX motherboards.

As far as Extended ATX and XL ATX are concerned, these are motherboards reserved for professionals that use their computers for streaming, editing, rendering, and so on. They have the most features and best expandability, but their high cost makes them hard to justify.