For the uninformed, the difference between ATX and Micro ATX is just size. For those with the necessary knowledge to truly see the difference, they know that, well, it mostly just is size. While there are compromises that come with going Micro ATX over the larger ATX motherboards, there are also benefits as well, namely in the compact nature of the form factor, and the cheaper motherboards, allowing for budget-oriented computers at even lower prices.
The history of Micro ATX isn’t inherently shrouded in any sort of mystery, but despite this, most people are unaware of the benefits and drawbacks to Micro ATX, as they see it as little more than a smaller board for cheaper. While having this outlook isn’t necessarily wrong, knowing the key differences between the two form factors is key to making an informed purchase and ensuring you build the computer you set out to, rather than one built around price tags.
Today, we’ll cover the differences between ATX and Micro ATX, and when you’ll want to use each form factor.
The RAM Scenario
Due to their size, many Micro ATX boards will forego including four RAM slots, and instead opt for two. However, this has recently become less common, with many board manufacturers instead opting to include all four. However, even with things as they are, Micro ATX boards on the far budget end of the spectrum will typically still only include two slots.
For many people, two slots will be enough, as they’re easily able to buy either a 2x4GB kit of RAM for 8GB total, which we consider the bare minimum for gaming in 2018. If more RAM is necessary, then upgrading to a 2x8GB kit is possible with most boards—most support 16-32GB of RAM, but this can be rather expensive, and all but entirely cuts you out of a potential upgrade bath, as all of your slots are consumed. Buying an entirely new kit is much worse than buying a matching pair and expanding upon your current RAM configuration, and having only two slots makes this a rather cumbersome procedure. As such, we’d advise against boards with only two slots, unless your budget simply cannot handle anything better.
Most, if not all Micro ATX boards will at least still allow for dual channel RAM, so there are no compromises in this regard, as the features regarding RAM mainly lie in capacity support and speed support, rather than channel support. Be sure to consult the QVL (Qualified Vendors List) for any board you’re interested in, to make sure your RAM will have no issues.
The Fans, or Lack Thereof
One compromise almost every Micro ATX board is hit with is lack of fan headers. While they usually have support for a CPU fan, and maybe a rear fan, you’d be hard pressed to find a Micro ATX board with ample fan support. In fact, many board manufacturers will include fan splitters in the box, as the lack of onboard headers has become something of an issue for builders who want proper airflow in their smaller PC builds, where their hardware is more choked for air than in a traditional ATX build.
Be sure to consult the specs page of the motherboard you’re interested in, to verify that it will either have the necessary headers for your fan configuration or that it will come with splitters that will alleviate the headaches that may follow if you struggle to properly plug in all of your fans.
The PCI Problem
This one shouldn’t come as much of a surprise. Most Micro ATX motherboards will come with fewer expansion slots than their bigger ATX cousin. This is because it’s simply impractical to make the board any taller, as it would no longer fit the Micro ATX spec. Finding space on the board for additional expansion slots is practically impossible, and as such you’re left with typically only two full-length and two mini-slots.
Most people, however, will never notice this. Where some enthusiasts will opt for dedicated network cards, sound cards, capture cards and the like, most, more normal consumers will rarely, if ever, add expansion cards to their computer. As such, the lack of additional slots will rarely be felt by anybody, not prosumer or enthusiast. Even then, four slots are usually more than enough. Still, it’s definitely something to keep in mind.
Most Micro ATX motherboards will feature only four SATA ports—or less—compared to ATX boards, which typically have six. This is mostly a thing on the very low budget boards though, so is typically something you needn’t worry about. Anyone looking to hook up many drives to, say, a custom NAS build, however, will want to keep this in mind. Micro ATX builds are also common in archive projects where people will use many drives, so keep this in mind if you’re looking for a board which will support many drives natively and without an expansion storage card.
Oh No, I/O
The rear I/O on most Micro ATX boards is also an area where manufacturers will cut back, simply due to a lack of space. Where on larger, ATX boards it’s common to see 10 USB ports, ethernet, audio and potentially more, Micro ATX boards will typically see a reduction in USB ports, a single ethernet port versus the more common two on larger boards, and sometimes even the omission of onboard graphics or wi-fi, board permitting. This is fine if all you need to do is connect a few peripherals, but it’s not difficult to quickly fill up your I/O, and with Micro ATX, this becomes much simpler. Just expect a reduction in USB ports, mainly.
It’s Not About Size, It’s About How You Use It
Despite the many corners that Micro ATX boards cut, they’re still highly capable boards, some even with excellent overclocking potential. A Micro ATX board will also typically see zero performance loss compared to a larger board if paired with the same hardware. Traditional ATX cases will almost always support Micro ATX boards as well, meaning that unlike how Micro ATX cases will not support larger boards, you can still go the other direction. This means more case variety, more build configurations, and ultimately more choice for you, the consumer. Picking up a budget board does not make you less of a gamer or less of a hardware enthusiast, it simply means it was what you could afford or what you needed at the time of purchase.
Where once Micro ATX was viewed as the budget option, many people are now starting to see it as what it truly is: the small form factor ATX board for small computers. Whereas we mentioned above that it can be mounted in larger cases, Micro ATX boards can also be built into small chassis, allowing for small-yet-powerful computers that you could even carry around with you, if you felt so inclined to.
Micro ATX isn’t about saving money, it’s about having a choice. It’s just important to know what comes with that choice.
In conclusion, Micro ATX boards, while they do have a handful of compromises and quirks that are best to keep in mind, it’s still a very powerful platform with proper mainstream support from CPU vendors, graphics card vendors and more. Once you know what you’re giving up and what you’re gaining, it’s not difficult to see Micro ATX as a very viable option on the market, rather than just a small board for budget consumers.