ATX vs Micro-ATX vs Mini-ITX – Which motherboard size to Choose ?

By | January 2, 2021

If you are building your own pc then you have to choose a good motherboard. Its the motherboard where most other components like RAM, graphics card are installed and peripherals like mouse, keyboard are connected to.

Though a motherboard does not directly affect the performance of your system, it does determine the kind of hardware and how many different kinds of components can be plugged into your system.

In this article we shall discuss the key factor that determines the capacity of a motherboard, which is the size or form factor.

Motherboard Form Factors Overview

Motherboards primarily come in three sizes - Micro-ATX, Mini-ITX, and ATX. Although there are more out there, these are the most commonly used and are more than enough for regular consumers at home or office.

ATX, Advanced Technology eXtended was introduced in 1995 by Intel to become the standard motherboard for all PCs. In 1997, the Micro-ATX was released to be the same width as the ATX, but shorter in length. Lastly, the smallest one in the group, the Mini-ATX was commercially available in 2002.

Size of different form factors:

  • ATX - 12in x 9.6in (305 x 244 mm)
  • MicroATX - (Maximum) - 9.6 in x 9.6 in (244 x 244 mm)
  • Mini-ITX - 6.7 x 6.7in (170 x 170 mm)

Motherboards have PCI (Peripheral Component Interconnect) and RAM slots where you connect your external components like your graphics card and RAM sticks.

PCI slots are the sockets where you plug-in your sound cards, graphics card, network cards, disk controllers, and so on. The number of PCI slots on your motherboard depends on size and form factor.

This is especially important to consider because different computers have unique purposes and finding a matching motherboard for your goal will save you a lot of money and hassle when building your PC!

1. ATX Motherboards

ATX motherboards, the oldest model, are the largest with a size of 12" × 9.6" (305 × 244 mm). These motherboards require the largest variant of PC cases to be installed properly.

Gigabyte X570 AORUS ELITE

gigabyte x570 aorus elite

ATX motherboards can have up to seven PCI slots, allowing you to connect to a lot of external cards your PC, which is useful for extremely heavy-duty workstation machines.

This model also supports four RAM modules however, it's important to remember that two 16GB RAM sticks are cheaper than four 8GB RAM sticks.

ATX motherboards also have more USB ports on the back-side and front side. If you need to connect lots of usb devices, then this can be a great choice.

ATX motherboards also have more SATA ports onboard that allow connecting sata compliant devices like ssds, hdds, optical drives etc.

Besides SATA ports, high end ATX motherboards can have upto 3 M.2 NVME slots which enables the user to add lot of high speed storage.

These motherboards are also the most expensive since they are the biggest.

Also keep in mind that ATX motherboards will typically have chipsets that can support larger number of PCI-e slots and more USB ports. Different chipsets have different capacities in terms of how many pcie slots and usb ports they can handle.

2. Micro-ATX Motherboards

Micro-ATX motherboards are in the middle of the group and are regarded as the best choice for most users. The medium-sized motherboard has a maximum size of 9.6" × 9.6" (244 × 244 mm). They are available in smaller sizes as well.

Micro-ATX supports up to a maximum of four PCI slots (but only 3 are seen commonly), the sweet spot for all your external hardware needs. Most common configuration seen is

  • 1 pcie x16 + 2 pcie x1
  • 1 pcie x16 + 1 pcie x4 + 1 pcie x1

There will always be 1 pcie x16 slot which will allow you to connect any x16 based card like graphics cards.

Micro-ATX can have 2 or 4 RAM slots. There are compact and smaller sized micro-atx motherboards have only 2 RAM slots.

For example, the Gigabyte GA-H110M-H motherboard has only 2 slots. Size - 22.6cm x 17.4cm

gigabyte ga-h110m-h

Whereas the Gigabyte B450M DS3H motherboard has 4 RAM slots and is bigger in size - 24.4cm x 21.5cm

gigabyte b450m ds3h

Micro-ATX motherboards are affordable and compact and can easily fit inside most budget pc cases.

3. Mini-ITX Motherboards

Finally, Mini-ATXs are the smallest type of motherboards, measuring at the standard 6.7 x 6.7in (170 x 170 mm). These small motherboards have only 1 PCI-e slot which is usually x16.

Mini-ATX motherboards only have upto two RAM modules, but you can buy ram modules with higher amount of memory.

Although mini itx is the smallest form factor motherboard, it's not the cheapest. This is because squeezing the components into such a small space can be expensive, as well as the guarantee that most Mini-ATX motherboards already come with Wi-Fi and/or Bluetooth.

Here is a typical mini itx motherboard from Gigabyte with the X570 chipset for AM4 socket:
Gigabyte X570 AORUS PRO WIFI

gigabyte x570 aorus pro wifi

Mini-ITX motherboards typically have 4 sata ports onboard and around 4-5 USB ports on back panel and 4 usb headers onboard. These typical hardware options are sufficient for most of the regular pc builds for home users.

Its worth noting that there are Mini Itx motherboards with M.2 NVME slots.

Which form factor to choose

So, which one is the best among the three ? It all boils down to your preference.

What are you building your PC for? Are you a gamer who wants to play the latest triple-A games? Or are you perhaps a video editor who needs the highest performance out of your computer so you can handle 8k video edits? Or are you building a budget PC that can have a bit of portability?

The motherboard you choose is highly determined by the purpose of your PC. ATX motherboards can handle the more PCIe hardware modules, but even professional gamers don't use all their PCI slots.

Here is a list of typical things you could install on your motherboard

  • Graphics Card
  • Sound Card
  • Wi-Fi card
  • SSDs
  • pcie based cards

Here are few things you should consider when choosing a motherboard:

  • how many ssds or hdds shall you install ?
  • how many pcie devices will be installed ?
  • how many usb ports do you need ?

1. Micro-ATX - Most Popular, Budget Friendly, Decent Specs

Micro-ATX is the most popular because it has the perfect balance of price and performance. They are in the middle with decent hardware features and budget pricing that suit most consumers.

You have around 1 pcie x16 + 2 pcie x1 slots with upto 4 ram slots and upto 6 sata ports. These allow you connect plenty of hardware.

You can build a gaming PC, regular home pc, office use pc, or a pc for professional work as well. More-over with the small size, you can opt for a mid sized pc case that is ergonomic and compact.

Considering that most users only plug in their graphics card, sound system, and perhaps a Wi-Fi network module, getting any more than 4 PCI slots may not be worth it.

2. ATX - High Spec, Higher Budget, More Powerful

With ATX you can connect lots of pcie devices, lots of ssds and lots of usb devices. It larger and supports more hardware.

ATX is useful for power users who want to build a powerful workstation or a professional PC for high load jobs like video editing and content creation that is hardware intensive.

You would also need a full size pc case that can fit ATX motherboard inside of it. This implies that the budget would increase for the pc case as well alongside the motherboard.

With 2 pcie x16 slots you also have the option to use multiple graphics cards based technologies like SLI from nvidia and crossfire from amd. However not all ATX motherboards support SLI, so first you need to check the specs on the official site to make sure that it fully supports SLI or multi gpu setups.

And ATX motherboard makes your machine future proof as you can potentially add more hardware to it in future without having to upgrade. It is not actually a huge advantage in terms of flexibility but helpful to some extent.

Also keep in mind that there are some chipsets like the AMD X570 that are available only on ATX form factor motherboards. These chipsets are designed to support lots of external hardware via pcie and usb, so it makes sense to put them only on larger motherboards that support more hardware.

3. Mini-ITX - Medium Budget, Limited Specs

The smallest in the group, the Mini-ITX is best suited for a compact PC system that doesn't take up a lot of space. Smaller pc cases can be portable if you need a LAN gaming machine to carry over frequently.

cooler master mastercase h100 side

Mini ITX PC Case Cooler Master MasterCase H100

How-ever the board is limited to a single x16 pcie slot and 2 ram slots.

So you can plug in a graphics card into a mini itx motherboard but nothing else. And for large amount of RAM you need memory sticks with larger memory, since you don't have to option to plug in 4 DIMMs.

Mini ITX is a great option if you are sure you would not need to install more hardware peripherals in future and your requirements with the small system is very specific, like a gaming pc or a media pc.

Mini-ATX motherboards can also lose their purpose if your graphics card is large because this will require a larger PC case, in which case, getting a Micro-ATX begins to feel more appealing.

These motherboard models will come with a built-in Wi-Fi and/or Bluetooth system, however, which can be appealing if you’re looking for a portable PC.

Finally, mini-itx is not the cheapest always. Though the smaller size, they often more expensive than similar micro-atx motherboards. So the real benefit of mini itx motherboards is just the size for those who need it, and not the price.


At the end of the day, recall the purpose of your computer and the size of your budget. Bigger motherboards are more expensive than their smaller siblings.

Generally, you'll find that most conventional purposes will fit right in with the Micro-ATX but each model has its own pros and cons. Hopefully, after reading this guide, you'll have a better idea of the difference between motherboard models.

We hope that this article helped you with your decision! If you have any feedback or questions, feel free to leave a comment below!

About Silver Moon

A Tech Enthusiast, Blogger, Linux Fan and a Software Developer. Writes about Computer hardware, Linux and Open Source software and coding in Python, Php and Javascript. He can be reached at [email protected].

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