Motherboard Sizes - The Complete Guide

Kaelum Ross

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May 24, 2020

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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

Motherboard Sizes Comparison Chart

Note: Sizes are approximations, check product listing for exact dimensions

Form FactorProsCons
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.

Perfect for very high-end gaming & production (editing, rendering, etc), an E-ATX motherboard will open up utility you can’t get from any other 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 can be overkill.

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. ATX 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 builds.

But ATX still has everything important to the majority of gamers/enthusiast builds.

Including support for 2-3 GPUs, 4 x DDR4 RAM, plenty of SATA ports, 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 available at competitive prices.

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.

Motherboard Sizes 2

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 form factor has dramatically improved.

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.

 

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.

Computer Case Size Comparison Chart

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

Motherboard CPU CompatibilityAlthough 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 for Intel, and AM4 for AMD.

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).

If you are confused here, don’t worry – just check the product listing!

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:

CPU Chipset Compatibility Explained

 

PCI Slots

Motherboard PCIe SlotsOne of the big factors for a gaming computer.

The larger your motherboard size, the more PCI Express (PCIe) slots you will have available, these are what allow you to install graphics cards.

An E-ATX motherboard for example, will often have 4 PCI-e 3.0 slots, allowing for a 4-way GPU PC. 

Aside from GPUs, other PCI slots are often included if you have other focusses (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.

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.

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.

SATA Ports

Motherboard SATA portsLarger boards will 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.

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, should you be too worried about confirming these beforehand.

Miscellaneous

NVMe M.2 Storage

Motherboard M2 StorageM.2 storage is less common than the standard 2.5″ SSD but 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.

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

Motherboard RAM SlotsA 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.

Of course if you’re focussed on the best speed possible, more slots will help.

Not just because of the increased overall storage, but 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.

Gaming PCs won’t need more than 32GB for a while.

If you do have specialist requirements, high-end E-ATX/ATX motherboards include up to 8 RAM slots/256GB capability!

I/O Panel

Motherboard IO PanelThe features available in an I/O panel will typically increase not just with chipset (which allows your mobo to support more inputs, e.g. USB 3.1 type C) but also the size.

E-ATX/high-end ATX motherboards often have a host of great ports available.

Smaller motherboards will usually have the standards though (some USB/audio ports) but check that your choice will have what you need, or you have a suitable extender.

Extra features

Finally, there are all the extra bells and whistles motherboards can come with.

The most common ones are:

  • Integrated sound card
  • Integrated network card (Wi-Fi/ethernet)
  • Integrated Bluetooth (if not, adapters are dirt cheap)

Typically, larger motherboards include more of these features as it’s easier for the manufacturers to add.

We would say it’s often preferred to buy a standalone sound card or network card if you have PCIe slot room (not essential if your budget is tight, though).

Even Mini-ITX boards can come with these features integrated, just know that you may not get quite the same quality as large integrations or standalone cards.

That being said for smaller builds, we’d recommend getting integrated versions of features you need where possible so you’re not having to use your very finite USB/PCI inputs.

Which Motherboard Should you get?

Best budget gaming motherboard

If your focus is on affordability above all else, go with Micro ATX.

While you may not get the same features as E-ATX/ATX you’re not going to need them for a cheap build.

Things like excellent cooling/space for multi-GPU builds aren’t so important for a cheap gaming PC where you should be focussing on 1 graphics card.

Micro ATX builds are the perfect balance between being small enough for good mobo/case affordability while not so small that you have to fork out more money/effort for “specialist” small parts.

Our best cheap gaming motherboard picks:

Best mid-range gaming motherboard

For most builders, the sweet spot is an ATX motherboard for gaming.

With all the feature a large majority of builders need, good space for parts/cooling in their compatible cases, and lots of choices, ATX mobos are perfect for most setups.

Even if you don’t need every PCIe/SATA/RAM slot, know that having an ATX case/motherboard gives your parts more room for ventilation (and makes the build process easier).

Our top picks for the best ATX motherboard:

Best high-end gaming motherboard/production PC

Now let us be clear: the options above will be enough for a majority of readers.

But, if you’re less concerned with budget and more with creating the most powerful PC you can, then you want to look at an E-ATX motherboard.

These will give you the most space and utility possible with no compromises made for compactness.

This is what makes them appealing not just for gaming, but for someone looking for the best production PC possible (video editing, rendering, etc).

Not to mention the large cases that come with the most room for cooling, drives, and ease-of-build.

In fact, even if you wanted an ATX motherboard for your high-end build (also doable), we’d recommend looking at E-ATX full tower (or “super tower”) cases for the best airflow/cooling options as long as you don’t mind the size.

Our top picks for the best E-ATX motherboards for gaming:

Best small motherboard for portable/HTPC build

Finally, there are those after the smallest motherboard for a portable build or HTPC.

It will come as no surprise that Mini ITX motherboards are the best option for you if this is what you’re hunting for.

Yes, as we’ve discussed, you’re losing out on some hardware compatibility and other features with a PC this small.

But combined with a high-quality case and some consideration for which parts you’re going to buy (ensuring they fit), you can still create a gaming PC capable of LAN parties or streaming.

Our top picks for the best Mini ITX motherboard:

FAQ

XL-ATX vs E-ATX?

XL-ATX motherboards are another form factor that traditionally are a similar width to E-ATX, but a bit longer.

We’ve chosen not to include them in our guide for a couple of reasons:

  • This size type is super uncommon and the options available aren’t great.
  • The use-cases are incredibly specific, given you can build anything from a powerful server to gaming PC on an E-ATX mobo, we’d wager XL-ATX isn’t necessary for anybody reading this.
  • Similarly to “full tower vs super tower”, XL-ATX is loosely defined and is a marketing term as much as it is a legitimate form factor. A lot of “extra-large motherboards” are E-ATX or even ATX anyway.

Short answer: don’t worry about Xl-ATX.

 

What order should I pick PC Parts?

Reading this guide and the criteria for selecting a motherboard, you may be confused as to how you should build your PC (e.g. do you pick a compatible motherboard for your chosen CPU or vice versa?).

It’s a bit of a “chicken and egg” situation, there’s no “right” order to pick parts in.

But here’s the outline we would recommend for most gamer builds (from first to last):

GPU – > CPU – > Motherboard – > Case – > RAM/storage/extras – > PSU

Don’t think that the above also represents order of importance, a PSU is very important!

It can just make sense to pick it last once you know the power requirements of your PC/what size PSU will fit in your case.

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