Why Micro ATX Builds Suck

On the surface, micro ATX builds seem to make a lot of sense – they allow you to install some really powerful hardware, but they take up a LOT less space than full tower ATX builds. What’s not to love?

Well unfortunately, going with a mATX case or motherboard can be consequences down the line – especially if you ever want to expand your system with extra PCIe cards. Plus there are other flaws with the micro ATX form factor, resulting in me regretting my choice of motherboard and case for my workstation PC’s build – as I discussin this video.

If you prefer text over video, please read on for the guide/transcript version of this video.

Video Transcript

Hey everyone, I’m not into clickbait on this channel which is why, even though there ARE lots of reasons why micro ATX builds suck, I was also eager to point out that I DO still have mATX builds. Ihave two computers: my 12 core Ryzen workstation PC, and a Homelab NAS. BOTH are micro ATX and I love mATX for the NAS – it just makes sense. BUT I’ve recently grown to hate the micro ATX form factor for my workstation PC. It has become a complete pain, and a false economy. So even though I DO think that micro ATX builds have a place, which I’ll discuss later in this video, here’s a bunch of reasons why you might want to avoid micro ATX altogether.

Micro ATX x16 Issues

So firstly, many micro ATX motherboards have multiple PCIe slots – even full size ones like in my workstation PC. But that second slot is completely pointless. It may as well not exist. That’s because pretty much EVERY modern graphics card is a “dual slot” GPU (well other than cards like the beastly RTX 4090 which is a triple slot card). This means that most GPUs take up TWO (or even three) PCIe slots. In other words, my Sapphire RX6700 XT graphics card COMPLETELY blocks the other full size PCIe slot. How does this affect me? Well, when I recently came to upgrade my home networking, I purchased two 10 Gigabit networking cards. I put one of these in my Homelab NAS build (which was easy to do, because it doesn’t have a separate graphics card to block everything up). I then moved over to my workstation PC. This didn’t fit. At all. This wasn’t due to lack of trying though. I tried a bunch of things. For example I loosened up the case screws and put my graphics card in at a weird angle, and then I rammed the networking card in and I thought that maybe – just maybe – this would work. But then I looked at the back ports and realized that my card resembled the leaning tower of Pisa. Which APPARENTLY isn’t ideal because this can actually kill PCIe cards or even the motherboard by placing too much stress on the PCIe connectors.

One alternative is to buy a full x16 riser cable and MOVE your graphics card away from the top spot, but honestly, riser cables are NOT easy to work with. They are very rigid, which IS by design I guess because it needs to protect the sensitive PCIe cables, and still deliver the full advertised speeds.

But unless you have a massive, non-micro ATX case, you probably won’t have anywhere to “put” the big, bulky riser cable. You’ll then end up trying to squish the cable down to try and relocate your graphics card a bit, and it all becomes a complete, stressful mess. I didn’t really see an easy way of using this 20 cm (8″) riser cable in my tiny micro ATX case in a way that would have properly secured and protected my graphics card.  So that was fun. I ended up GIVING UP on the idea of installing a 10 Gigabit networking card in my workstation PC. All thanks to micro ATX. And poor planning on my part, I guess, but let’s skip over that.

Now you might be wondering: if there are TWO “full size” (x16) PCIe slots, why can’t I just put the graphics card into the bottom slot and my networking card into the top slot? Well firstly in my current case I PHYSICALLY couldn’t do this because of how close the PSU is to the bottom PCIe slot. But there’s actually a bigger problem, other than the laws of physics. That second PCIe slot only runs at x4 speeds – this actually isn’t flaw with micro ATX motherboards, it’s due to how PCIe lanes are divided between the CPU and the chipset.

BUT running graphics cards at just x4 speeds WILL often result in lower gaming performance – Odin Hardware has a great round-up video which shows that frame rates ARE noticeable lower when running a graphics card at this lower bandwidth level. So even if my micro ATX case DID have enough room for these two, I would then have to suffer lower gaming performance if I wanted 10 Gigabit networking, which kinda sucks. You shouldn’t really have to make that choice, but there you go. I’d also be making it impossible to access all the header connectors along the bottom of my case – meaning that I’d have to remove my graphics card every single time that I wanted to access them.

On that note, there is ONE thing you can try if the PCIe slot is covered by your GPU. You can buy a really small right angle PCIe riser cable that you insert into a PCIe slot BEFORE inserting the graphics card. This then allows you to freely plug your PCIe card into this riser cable, because it’s not blocked off. And because it’s right angled, it usually only needs a tiny bot of amount of clearance below the graphics card to fit. What’s not to love? Well I’ll tell you. In general these slimline, right angled cables only support x1 speeds (meaning they’ll be too slow to really support NVMe or 10 Gigabit expansion cards). PLUS they won’t always fit. Going back to my workstation PC, for example, the PSU is right up against the edge of the motherboard – so I’d struggle to even fit THIS type of “slimline” riser cable in.

Other mATX Problems

At this point you might be thinking “ah hah, I’ve had a brainwave – I’ll buy a micro ATX motherboard but stick it in a full ATX case” and that WILL work, and it’ll offer you SOME future proofing options, which is good. But even this can have some downsides, for example the case’s fan connectors probably won’t reach the motherboard’s fan connectors (because the motherboard is relatively further away in this larger case). Yes this isn’t a massive issue because you can buy fan extension cables, but it’s still worth considering.

The next problem with micro ATX builds is that some motherboards have the main x16 slot too close to the CPU socket, meaning that the CPU heatsink is almost touching the back of the graphics card. Now this shouldn’t cause shorts or anything, as long as your GPU has a solid back panel – but it’s still not ideal. Heck, in some cases you might not be able to fit some CPU coolers AT ALL if they come with large 140mm fans. This of course isn’t an issue with good planning though – companies like Noctua have really awesome compatibility checkers which you should always use BEFORE buying any parts, and that’s whymy main PC now has a massive chocolate fan, in other words the Noctua C14S cooler – because many other CPU coolers simply didn’t fit in my small case.

Anyway, to prevent THIS problem, what some micro ATX motherboard makers do is put a small x1 PCIe slot in, to act as a “buffer” between the CPU cooler and themain x16 slot. But THEN, due to the lack of space, they JAM an M.2 NVMe slot in there – making that x1 slot COMPLETELY unusable if your M.2 drive has a heatsink, because the heatsink adds extra height that will clash with many PCIe cards. Awesome. So if you want tocool down your overly warm gen 4 (and gen5) NVMe drives, you lose YET ANOTHER PCIe slot.

Why mATX Has Cost Me Money

So I mentioned in the intro that mATX has become a false economy for me, but why is this? Well when I originally built this PC, I decided to go with a micro ATX motherboard – the Asus B550M-Plus – partly due to its compact size, but partly because it was SLIGHTLY cheaper than an ATX motherboard. And that decision seemed to make sense at the time, especially because I was re-using my old micro ATX case – I didn’t want to have to spend more on the motherboard PLUS buy a brand new case.

BUT that decision has come back to haunt me – because I’m now unable to plug in a simple, tiny PCIe card. You can just see how cramped everything is inside my case – it’s hard to add anything extra to the build. And I only have a dual-slot GPU. The situation would be even worse with a larger triple slot GPU… not that that would actually fit in my micro ATX case though.

I do actually really want to fit this card in, meaning that I’ll either have to go back to the jankyriser cable approach(which I’m not convinced would really work in this case) OR I have to upgrade to an ATX motherboard AND case. Basically the money I ORIGINALLY spent on my mATX motherboard has been wasted. It’s a false economy. Now I realize that I’ve moaned about the micro ATX format for like 5 minutes straight – but is there ANY positive to it?

When Micro ATX Makes Sense

Well yes, I still think there is. Firstly, mATX builds can work great when you have limited space. For example with my Homelab NAS I wanted a small build that can fit in my “networking corner” over there – and ideally sit on the simple £10 IKEA table that I have:

The Aerocool CS-106 casewas cheap and it worked really well – you can barely see ANY size difference between my Synology NAS and my Homelab one, right? Okay maybe you can, but this is still a good usecase for micro ATX – a large ATX case simply wouldn’t have fit here.

Next up, if you’re working on a simple, budget gaming PC, micro ATX MIGHT work out fine for you. After all, mATX motherboards ARE a bit cheaper, and as long as you won’t need to have 10 Gigabit networking or loads of NVMe drives in the future, you MIGHT be fine to just have a single graphics card dominating all your other  PCIe slots like a territorial cat. (Sorry if that seems like a weird example, I have two cats and one of them thinks they own every single inch of this house – which is fun!)

So that’s where mATX MIGHT work but it’s difficult to say for sure because you can’t predict the future. When I built my workstation PC, for example, I didn’t THINK that I would ever need 10 Gigabit networking speeds – but now I do. Well, technically I don’t NEED it since my motherboard offers 2 and a half Gig speeds, which will SORT OF be good enough for now, but you hopefully get my point…. which is that I kinda want to be able to brag to people at parties that I have 10 Gigabit networking, goshdarnit.

The other reason that mATX builds might make sense is when youuse WiFito connect to the internet. While PCIe Wi-Fi cards ARE quite reliable, they probably won’t fit – but thankfully some mATX motherboards have WiFi built in, negating the need to have a separate PCIe card. But if not, you can always buy a USB Wi-Fi adaptor instead – as long as you stay away from cheap no-name USB adaptors, because they’re often terrible. Modern motherboards also have an M.2 WiFi slot and these are good to explore too.

But in general, as long as you’re aware that micro ATX builds DO have some flaws, they CAN still be a good thing to buy, and as I mentioned at the START of the video, while I regret it for my workstation PC, I’m really happy with that decision for my Homelab NAS. Ishow off how (and why) I created my NAS in another videoif you wanted to check that out, and while it IS 45 minutes long, it does have lots of chapters so you can skip to the bits that you want to see.

Tristan has been interested in computer hardware and software since he was 10 years old. He has built loads of computers over the years, along with installing, modifying and writing software (he’s a backend software developer ‘by trade’).Tristan also has an academic background in technology (in Math and Computer Science), so he enjoys drilling into the deeper aspects of technology.Tristan is also an avid PC gamer, with FFX and Rocket League being his favorite games.