Motherboard Sizes - The Complete Guide
Sizing up your motherboard is a big deal.
What is an ATX motherboard anyway?
Who wins in the battle between E-ATX vs ATX vs mATX vs mITX?
Whatever the question, we’ve put together this guide to explain the differences between motherboard sizes.
With this piece and our detailed feature on PC case sizes, you have everything you need to size up your next build.
Table of Contents
Motherboard Size Comparison Chart
Note: Sizes are approximations, check product listing for exact dimensions
| Form Factor | Pros | Cons |
|---|---|---|
| E-ATX | • Best for the most powerful PC builds • Up to Quad-GPU/8 x DDR4 RAM support • Fantastic overclocking/cooling options • Best for high-end, production, and servers PCs | • Most expensive • Very large/bulky • "Overkill" for many users |
| ATX | • Best "all-round" option • Plenty of GPU/hardware room • Fantastic overclocking/cooling • Lots of ATX case styles available • Perfect for most gaming PCs | • Still quite large/heavy • More expensive than Micro ATX |
| Micro ATX | • Best budget motherboard • Compact with stylish case options • Dual-GPU possible • Most have 4 x RAM slots • Good part compatibility | • Dual-GPU setups may be hard • Less cooling/overclock potential |
| Mini ITX | • Smallest motherboard size • Perfect for a portable build (e.g. a VR demo / LAN party PC) • Cheap motherboard/case options • Most mITX cases look fantastic | • Single GPU build only • 2 x RAM slots • Limited space for other features/cooling • Harder build due to size • Effort needed to find parts that will fit. |
Motherboard Sizes Explained
E-ATX Motherboard
The largest of the main types. An Extended-ATX motherboard is for builders focussed on building the most powerful PC possible.
This mobo form factor is designed to work alongside a full tower PC case, providing you with incredible space/features.
This often includes support for Quad-GPU builds and 8 RAM slots (which could achieve up to 256GB of memory).
Not to mention the breathing room to cool all of these components with immense overclocking potential.
E-ATX cases, with their massive size, will often be good for part compatibility (with many popular components being based around hosting ATX motherboards, cases designed to included EATX mobos can essentially fit things like most mainstream power supply units with more room to spare).
Perfect for very high-end enthusiast gaming & production (editing, rendering, etc), an E-ATX motherboard will open up some great utility with its large size.
Note that there are, of course, diminishing returns when building such a powerhouse.
If you’re the average gamer or don’t need the best PC money can buy, E-ATX is often going to be overkill (with SLI/Crossfire support becoming less common in games now).
The real benefits will be to those who can make use of the GPUs independently, like a high-end video editing or crypto mining rig.
The boards are very expensive and alongside an E-ATX case, are enormous. Make sure you have space.
That being said, if you care less about the budget and more about the most power possible, this is the size for you.
ATX Motherboard
The mid-tower motherboard. This motherboard form factor is what many would consider the “standard ATX” option and has reigned as the most popular size for a long time, and for good reasons.
When considering EATX vs ATX, sure the latter will have slightly less space for high-end desktop computers.
But ATX boards still have everything important to the majority of gamers/enthusiast builds.
Including support for 2-3 GPUs, 4 x DDR4 RAM, plenty of SATA ports, more than enough expansion slots, and their ATX case-counterparts come with plenty of decent cooling options.
Even if it’s not the best motherboard for overclocking (that belongs to E-ATX), it’s still a very close second and will achieve what most gamers need.
The other great advantage is due to the popularity, there are so many good ATX mobos and combos with CPUs available at competitive prices. You’re also best placed for part compatibility, with a lot of power supply options being sized with ATX PC cases in mind.
An ATX build is still going to be fairly big with limited portability. Bear that in mind if you’re building an on-desk setup.
But overall, if you’re looking for the best “all-round” option, an ATX build is the way to go.
mATX Motherboard
While ATX may be the most popular overall, Micro ATX motherboards have been giving them a run for their money in the last few years.
Why? Well, the quality of this small form factor has dramatically improved over the last several years for both Intel and Ryzen motherboards, and the pc case sizes it runs with are a nice balance between space and compactness.
With a majority now having 4 x DDR4 RAM slots, good SATA connector availability, and even 2 PCIe slots for a small SLI/Crossfire GPU build.
This is the smallest PC build you can create while still accomodating a majority of mainstream components.
Note that as we get to this size, running a dual-GPU build will usually get cramped and isn’t ideal.
It’s certainly possible, but the preference would be to stick to a single graphics card (with the utility to overclock).
As we discuss further below in our top picks, the Micro ATX motherboard size nails affordability.
If you want something compact/cheap but not so small that you have to be extra careful with your hardware choices, this is the pick.
mITX Motherboard
And then there are those looking for the smallest PC possible.
A Mini-ITX build is for those very focussed on portability or a compact style (e.g. LAN-party build, HTPC, or perhaps a streaming computer).
With such a tiny size, you’re of course compromising on feature availability.
Most Mini-ITX mobos come with 2 RAM slots (still providing up to 64GB), a single PCIe slot, and limited SATA ports.
The cases that support them are also on the smaller side. Leading to limited ventilation/cooling. You’re going to struggle with overclocking.
With this small size, you will need to pay more attention to the other parts you buy (most notably GPU/PSUs).
This can often include having to buy parts that are a bit more expensive (usually offset by the cheap motherboard and cases, however).
With all that being said, the convenience of a portable PC is massive and compact builds often look fantastic.
If this is what your heart is set on, don’t fret! You can build a great gaming computer on a Mini-ITX motherboard, and our guides on motherboard CPU combos/PC cases include ITX options.
How to Choose a Motherboard Size
Ahead of giving you our top picks, we’ve broken down the key criteria for what to look for in a motherboard.
Just know that not all these factors will be important to you individually (many people don’t need to worry about having more than a few SATA ports, etc.).
Don’t be overwhelmed by all the factors, just focus on what’s important to you, and check out our recommendations if in doubt.
Form Factor / PC Case Size
Let’s start with an obvious one.
Whatever motherboard you pick, you want to make sure that you have an appropriately sized case to go with it (e.g. E-ATX case for an E-ATX motherboard).
Check out our joint-feature on PC case sizes if you want more info.
But in short, the type of motherboard you want will probably also guide the case size you need anyway (e.g. if you’re looking at a smaller motherboard, the case will have fewer hardware space/cooling options, but that’s the trade-off for portability).
CPU compatibility
Although not explicitly related to size, this one is worth covering as it’s one of the most important buying factors.
When purchasing a motherboard, make sure it’s compatible with the CPU you’re looking at.
Firstly there’s LGA vs PGA vs BGA.
There’s already good resource if you want the very technical explanation, but in short:
- LGA is most common for Intel CPUs.
- PGA is most common for AMD CPUs.
- BGA is more for manufacturers and not worth considering for your individual build.
Note: this isn’t universal, you may (rarely) in the future see an AMD CPU on LGA – but this will usually be very clear in a listing.
The most common socket types right now are LGA 1151 & LGA 1200 for Intel, and AM4 for AMD.
Intel LGA 1151 vs LGA 1200
Right now, Intel’s mainstream processors are in an awkward space of transitioning to a new socket type, the LGA 1200.
This socket is what supports the new 10000 range (i5-10600k, i7-10700k, i9-10900k, etc).
These are the latest and greatest from Intel, and if you’re building a new Intel personal computer, it would make sense to go for the latest socket/CPU range.
But if your budget is lower than these motherboards and CPUs, know that the current LGA 1151 socket still has plenty of decent combos that are worthy of powering a beefy PC for gaming, production, or general use.
These will support the most common CPUs you’ll be looking at for gaming.
There will be more terms in this area that will probably confuse you like Z370 vs z390 (which is mainly just a difference in wifi/USB compatibility).
Instead of learning every chipset (there’s a lot) – we’d recommend a beginner check the product listing to see.
We’ve only provided this info for the full picture. Once you’ve found the CPU you want, it’s pretty clear what a motherboard supports in the product listing like below:
This motherboard supports Intel 8000 and 9000 series, and there’s an LGA1200 version for the 10000 CPUs. The product listing will then talk about the kind of features included based on the chipset on offer.
Let’s take the LGA1200 motherboard just linked as an example; this model has a Z490 chipset, which will have features for enthusiasts like overclocking capabilities, high-quality ports/Wi-Fi, and good capability for M.2 storage).
Assuming you’re buying a popular motherboard/CPU combo, it’s usually really easy to find out if your desired CPU is supported with that motherboard, and what kind of audience it’s catering to by reading some of the product description.
PCI Slots
PCI slots are what host your external components, the most common one being graphics cards (in PCI Express/PCIe slots).
The larger your motherboard size, the more PCIe slots you will (usually) have available.
An E-ATX motherboard, for example, will often have 4 PCI-e 3.0 slots, allowing for a 4-way GPU PC.
As we made clear in the EATX mobo section, however, more doesn’t mean better for gaming unless you’re a very high-end enthusiast who is happy tweaking things (or a production user/high-end editor). Most gamers will be fine with a board that has 1 or 2 decent PCIe slots (which a huge majority of motherboards have now, as most are catering to gamers).
Aside from GPUs, other PCI slots are often included if you have other focuses (e.g. installing a high-quality independent sound/network card).
Just know that you’ll usually have to put them in a place that blocks you from fitting an extra GPU if you are wanted to install multiple ones.
That’s the beauty of a large motherboard though. Not many people need 4 GPUs, so those PCIe slots can come in handy for other things if needed.
PCI-E x4 vs x8 vs x16
When looking at PCI-E slots you may notice the different numbers next to them (i.e. PCI-E 3.0 x4/x8/x16).
Putting it simply, a motherboard can only circulate a certain amount of data/bandwidth at a time.
So if you have a lot of PCI-e slots, some of them will be x4 – x8 which means they can’t output the same bandwidth as your main x16 slot/s.
But: There have been many benchmarks on what the performance difference is between these types.
The difference between PCIe x4, x8, and x16 is very minimal for performance/gaming.
We’re talking a couple of FPS in games.
This is because most GPUs don’t come close to actually requiring the x16 power that an x16 slot provides.
Whichever x type, you’re still going to be getting a majority of the card’s power overall. Although to state the obvious, your GPU is nearly always the component that should be in the highest bandwidth slot.
SATA Ports
Larger boards will often come with more SATA ports to allow you to connect more SSDs, HDDs, and optical drives.
For most gaming builds, you’ll have more than enough SATA ports for your requirements on most boards.
However, it’s worth checking if you’re purchasing an mATX / mITX motherboard to ensure you have enough.
It’s only if you’re building say, a video editing PC, or if you have other requirements that means you want to install a lot of storage/other components, should you be too worried about confirming these beforehand.
Miscellaneous
NVMe M.2 Storage
M.2 storage is becoming increasingly popular over the standard 2.5″ SSDs / 3.5″ hard drives and worth your consideration if you’re all about speed.
It’s a type of solid-state drive that larger motherboards have become more compatible with over the last few years.
M.2 SSD vs SSD (2.5″) – An M.2 SSD installed via NVMe is around 5 times faster than a SATA-installed SSD.
Note that this is during benchmarking. In real terms to the user, this will likely be around 2-3 times faster (still nothing to complain about!).
These storage units are of course a lot more expensive (here’s our top pick) but run like a dream when you’re installing your OS and common apps on there.
If you like the sound of this, we recommend looking at an ATX or E-ATX motherboard.
You might be able to squeeze out the utility for an NVMe M.2 within mATX but it will likely mean the board is sacrificing bandwidth somewhere else.
Most motherboard listings will detail their support for this storage type so don’t fret about compatibility too much.
Just make sure to get an NVMe M.2 SSD (SATA ones perform similarly to a 2.5″ SSD) – here’s our top pick.
RAM slots
A majority of motherboards from E-ATX to Micro ATX will provide a minimum of 4 x DDR4 RAM slots.
The smallest form factor, mITX, tends to come with a maximum of 2 x DDR4 RAM slots.
In reality, this means you can still make a build with up to 32GB of storage which is plenty for gaming and most other functions.
A better motherboard can be beneficial for RAM as on top of having more slots, better motherboards tend to be more capable of working well alongside higher RAM speeds (though this is all mostly concerning to enthusiasts who want to mid-max performance; if you’re the average user getting confused, a mid-range motherboard will be more than powerful enough for gaming and more!).
It’s also nice to have RAM slot options as more RAM sticks are marginally more effective than overall storage (e.g. 4 x 8GB RAM is better than 2 x 16GB RAM for most users).
We wouldn’t worry about RAM compatibility too much unless you’re running some high-quality production/editing/streaming computer.