Don’t build an ultra-tiny small form factor PC without reading this first

Mid-tower PCs haven’t gone out of style—as one of the most flexible (and affordable) sizes, they’re an easy choice for builders. But these days, small form factor (SFF) DIY PCs are fashionable. The enthusiasm around them continues to spread too, with big component vendors hopping on board to add their spin to the process.

For the uninitiated, a tiny desktop computer may not make much sense, since a mid-tower system is fast and straightforward to assemble. Prices start much lower, too. If you’re not familiar with SFF PCs, Intel’s launch of its Dragon Canyon NUC, a modular 8-liter gaming PC, may seem like an unreasonably expensive niche indulgence.

But once you dig into the details about SFF PCs, it becomes pretty clear why people sign themselves up for these tiny systems. Here are the five key points to know about the lilliputian side of PC building.

#1: SFF is all about case volume

These days, small form factor builds are generally defined as any system in a case under 20 liters in volume. You may see some case manufacturers stretch the definition (for example, SilverStone raises the cut off to 23L), but the SFF community holds to 20L.

What goes into the system isn’t as rigidly defined. However, nearly all cases take mini-ITX motherboards as their largest size. Most also limit you to smaller power supply form factors (SFX, SFX-L), with very compact cases supporting only SFX. That said, don’t take this as a rule. Recent SFF cases include models that support ATX power supplies, just like larger cases.

Shapes and layouts also vary—a lot more choice exists now than in previous years. Currently more focus is on PCs that can take a discrete graphics card. For such cases, shoebox is the most common shape. And as you shrink their size, sandwich layouts (where the the case is divided into two sections, with the GPU occupying one half and the CPU/motherboard the other) are popular for better airflow. You don’t see as many classic layouts, where one chamber houses all the components.

#2: Case prices are no longer sky high

Not long ago, spending between $180 and $250 for a small form factor case wasn’t uncommon. While you could find some models for less, those that accommodated a discrete GPU trended closer to 20L and were made with cheaper materials.

But in the last couple of years, the market has begun to change. Big case vendors like Cooler Master and Lian Li have waded into SFF with a vengeance, and they’re not merely capitalizing on current zeitgeist. They’re democratizing it, too. Cooler Master made waves with the astonishingly sleek yet affordable NR200, which launched at $80 USD. Even at higher price points, which shrink the footprint of the case, incorporate more features, or boast even fancier materials, the cost is on par with larger cases of similar quality. Spending $130 on the Lian Li A4-H2O doesn’t feel like overspending compared to the company’s O11 Air Mini—just a different path taken. 

#3: But SFF PCs still cost more overall

We love to see the falling prices on small form factor cases, since that gets more people into the SFF scene. But the overall cost of building an SFF PC still runs higher on average, due to a few factors.

The main sticking point is the need for a mini-ITX motherboard. Despite having fewer features compared to ATX boards due to their smaller size, they tend to start at higher prices. And while you can find a case here and there that can accommodate an ATX power supply, most SFF builds require an SFX or SFX-L power supply, which also start at higher prices. You’re not paying more for less, per se—you shell out more because you start with nicer gear. Manufacturers don’t typically make stripped-down mini-ITX boards or SFX PSUs.

Ancillary purchases can creep in, too. They’re things you don’t usually need with a larger build, like fan grills or different power cables. In more spacious accommodations, your wires can be more easily routed around fans so they’re not chewed up by the blades. Similarly, you don’t need to sweat inflexible power cables. Even in a micro-tower case, you don’t need to wad them up and cram them into tight crevices. And if you’re into making the most of your hardware—or live in deathly fear of suboptimal temperatures—you may end up putting more money into higher-performing cooling, too. You don’t have to plan on a picture-perfect build to end up spending more. Costs can still add up as you compensate for having less room to work in.

#4: Your hardware won’t fry

You can’t escape the laws of nature, but packing hardware into tight quarters isn’t their death sentence. Modern SFF cases pay much more attention to airflow, and more importantly they better accommodate closed loop coolers, which can help drop temps without taking a ton of space.

The bigger factor with temperatures in small form factor builds is planning. Unlike with a mid-tower PC, you can’t pick a set of parts that are cheap or appeal to you, slap them inside, and expect an optimal outcome. To keep CPU and GPU temps within recommended ranges, you have to consider the layout of your chosen case and how your parts list will interact within that layout. But even though an SFF PC will run a little warmer than a mid-tower build, you can still hit great temps with some effort (and probably a little more money than initially anticipated).

#5: Building often takes more time

In larger cases, you can install parts in almost any order. With small-form factor PCs, installing components typically follows an ideal order—and figuring that out always takes time. Even when the manufacturer offers guidelines for the process, you can still find yourself doubling back to fiddle with this or that. For example, maybe you should have routed the 24-pin power supply cable from a different angle before mounting the motherboard.

YouTube videos can reduce the hassle of determining the sequence of steps, but either way, you’re still going to invest more minutes (or hours) overall. Cable management can take extra work in particular—when one PCWorld staff member built his first SFF PC, that was the very first thing that he learned.

Why go SFF?

A tiny desktop PC that can fit just about anywhere and be moved with ease between those spots is already pretty cool. Being able to pack in high-end parts like a Ryzen 9 5900X and a GeForce RTX 3080 in that same computer is absolutely awesome. Small doesn’t have to be a sacrifice of performance.

And with more attention being paid to the SFF scene, the room for different tastes only grows. (No pun intended.) That’s the reason news about freshly announced or launch cases get so much hype. Improved aesthetics and innovative designs continue to enhance the building experience, while also offering more flexibility and choice. Whole riffs on SFF builds like Intel’s Dragon Canyon NUC are especially exciting—you can roll an 8-liter PC in under an hour.