The Right Case for Your Next PC Build, Part One

By Nathan Edwards

The case isn’t just a box you put your components in. You should choose your case (and case size) based on what you need your computer to do.

The right PC for you is the one that meets your needs, and not necessarily someone else’s list of the Absolute Best Components Ever. You get exactly the PC you want by choosing all the parts that go into it, and if you put it together yourself, you get the satisfaction of using something you built.

Some people build PCs with the assumption that as long as a case holds all the components together, it’s good enough, and you don’t need to worry about anything more than that. That approach lets you go down to Fry’s, grab the cheapest case you can find, and call it a day. We’ll call that the “Charisma is my dump stat” approach, and it is unwise. Budgeting is smart. Spending no more than you need to is smart. But everything else about your build is carefully considered and optimized for you--shouldn’t your case be, too?

Because there’s a lot to talk about when it comes to cases, I’m splitting this topic up into two parts. This first part is about picking the case size and form factor that’s right for your build. Next week, I'll focus on specific case features to look for when browsing in store or online.

Size Matters (But Bigger Isn’t Better)

There are a half-dozen basic form factors and sizes of PC cases, from tiny to desk-shatteringly huge. There are dozens of PC case makers, with hundreds of different models to choose from. I counted 71 cases in Thermaltake’s current lineup alone. That’s just one vendor. How can anyone actually sort through all this?

As always, start by identifying your needs. What you’re going to do with your PC determines which specific components you’ll need, and how many of each. That determines the size of the motherboard, and case size follows motherboard size. Here are your basic options, from smallest to largest, and the types of builds each is suited for.

Note: I’ll focus on form factors that take standard x86 desktop CPUs. Super-small boards (nano-ITX, pico-ITX, Intel’s NUC, Arduino, Raspberry Pi, ad infinitum) and super-large boards (like dual-processor and server boards) are for specialty builds. We can talk about those in a later column if there’s interest.

Mini-ITX: LAN, HTPC, NAS, and other initialisms.

Why Mini-ITX: You want a small form factor PC, or a special-purpose box like a NAS or home server. You only need one expansion card at most: a video card or a RAID controller or a sound card.

Why Not: You want better cooling performance, more than one PCIe card, or lots of drives; you want a cheaper case.

Mini-ITX cases are great for situations where space is a priority, like a small apartment. They’re also great for LAN boxes and home servers. Mini-ITX motherboards are just 6.7 inches on each side. They have a full desktop CPU socket (or sometimes an integrated CPU) and two to four RAM slots, as well as the usual array of I/O ports in the back. Many also have built-in Wi-Fi cards or mini-PCIe slots. Mini-ITX boards have at most one PCIe x16 slot--enough for a video card if you’re building a gaming machine, or a RAID card if you’re building a NAS. So mini-ITX chassis, if they have any PCI expansion slots at all, usually just have two--enough to accommodate a single dual-slot GPU.

Your build may not require any expansion cards at all. Say you’re building a system with integrated graphics and one or two 2.5-inch hard drives, for an office workstation or other tiny build. In that case (heh) you can use a chassis that’s barely bigger than the motherboard, like Antec’s ISK-100.

If you’re building a home server, you’ll want a case with one expansion slot (for the RAID controller) but lots of hard drive bays. Lian Li’s PC-Q25B and Fractal’s (apparently discontinued) Array R2 are both mini-ITX cases designed for home server use, with seven and six 3.5-inch drive bays respectively.

Mini-ITX cases like Silverstone’s Sugo SG08 or the BitFenix Prodigy can accommodate a full-sized graphics card as well as a few hard drives and SSDs. You can pack a full gaming system into one of these, but you’ll have no room for a sound card, discrete NIC, or additional GPU. I’ve used both of these cases in gaming rigs for Maximum PC--the Silverstone in 2010 (using the SG07, the predecessor to the SG08) and the BitFenix last year, and I’d use both again--though I’d probably opt for the Silverstone, because it’s smaller.

Mini-ITX cases do have a few disadvantages. The first is that they’re small and so you don’t have many options for adding additional components later--you can forget about a multi-GPU build, or a sound card. They’re also harder to build into, and trickier to cool effectively. Finally, they can be more expensive than standard ATX cases. The SG08 is $200 (though it does come with a 600W Silverstone PSU), while the BitFenix Prodigy is a more reasonable $80.

Take a look at your actual needs now as well as your upgrade path. If everything you need will fit into a mini-ITX chassis, why go larger?

Micro-ATX: The Goldilocks Scenario

Why Micro-ATX: You want almost all of the features of a full-sized rig in a slightly smaller package, or you want a living room PC that fits into your entertainment center. You have up to two expansion cards--two GPUs, maybe, or a GPU and a sound card.

Why Not: Micro-ATX cases are more cramped and have limited room for more components. You want multiple GPUs or lots of 5.25-inch bay devices.

Despite the name, micro-ATX mobos are the same width as full ATX mobos, and only about 2.4 inches shorter. They have fewer expansion slots than full ATX but will almost always have at least two PCIe x16 slots and a few smaller ones, such as an x4 or a x1 and an old-school PCI slot.

While you’re not saving as much space with micro-ATX as you would with mini-ITX, it’s still a great way to size down your desktop without much impacting your ability to add components later. You can use a micro-ATX motherboard in a mid- or full-tower case, of course, but that’s missing the point.

In my first article I mentioned the Silverstone TJ08-E as a great micro-ATX case. It has room for four hard drives, a floor-mounted SSD, two full-sized optical drives, and four PCIe expansion slots, all for $100. It’s about five inches shorter and four inches shallower than a standard mid-tower. I ran a dual-slot GPU and a single-slot sound card in mine, and that’s all I require. Fractal Design’s Arc Mini is another good micro-ATX case with more drive bays for the same price.

For what it’s worth, if I was building a new desktop computer for myself from scratch, I’d go micro-ATX, but I’d be sorely tempted by mini-ITX.

ATX: One Size Fits Most

Why ATX: You need more than two expansion cards and more than a few hard drives and optical drives, or you want better cooling than you get with a smaller case. There are an astonishing number of great ATX cases and motherboards in every price range, and ATX cases are easier to build in.

Why Not: A full-sized PC might be too big for your space, or overkill for your needs.

ATX has been the default case and motherboard standard for over a decade. There are more ATX cases on the market than there are jerks on Xbox Live (ok, maybe not), and most fall into the loose categories of “mid-tower” and “full-tower.” What’s the difference? Once again, size. Mid-tower cases have every feature you need for nearly any build. A typical mid-tower case might be twenty inches high, twenty deep, and eight wide. It’ll have three or more case fans (with mounting points for more), half a dozen or more hard drive bays, and two to four optical drive bays, along with perhaps seven expansion port slots.

Full-tower cases are bigger and generally (but not always) more high-end. Some have over a dozen hard drive bays and half a dozen optical drive bays. Full-tower cases often have more case fans and more space for elaborate water-cooling setups should you choose. Premium full-tower cases can cost north of $300, but above of that point you’re paying partly for a status symbol.

ATX is the way to go if you have a lot of expansion cards or drives, want to add more later, if you’re on a budget, or if you’re using water-cooling. Because they’re larger than micro-ATX or mini-ITX cases, ATX cases also tend to be easier to cool. There’s more room for tidy cable management, more airflow, and more case fans.

You’ll find the most variety among ATX cases, so if you’re looking for a particular aesthetic style, chances are you’ll find a mid-tower or full-tower that matches it. ATX cases tend to give you the best bang for your buck, too--some of my favorite mid-tower cases, like the Fractal Define R4 and the NZXT Phantom 410, are around $100. There are great sub-$100 cases like the BitFenix Shinobi, too, and Silverstone and Corsair and Lian Li and many more make great $100+ cases.

Expect to pay a little more for a great full-tower case, though there are some surprisingly good cheap options, like the Rosewill Thor v2, for $130.

EATX, XL-ATX, HPTX: Serious Business

Why EATX, XL-ATX, or HPTX: Puny ATX motherboards and cases aren’t enough for your triple- or quad-GPU setup, which by the way needs to be water-cooled. Or you need a render farm, small network server, and gaming rig. In one.

Why Not: Most people don’t need that. And top-of-the-line cases get pricey.

Expanded ATX motherboards are 12 inches by 13 inches. They’re usually used for dual-processor server boards, though some “premium” desktop boards are EATX. EATX and larger motherboards generally require full-tower or larger cases, like the Cooler Master Cosmos II, Rosewill Thor v2, or Corsair 800D, or even custom-built cases, like the ones from Case Labs and Mountain Mods.

An EATX motherboard is almost certainly overkill for a desktop user, though as a former Maximum PC editor I am honor-bound to inform you that sometimes overkill is the perfect amount of kill. Regardless, builds using EATX and the other mega mobo sizes like XL-ATX and HPTX are outside the scope of this guide, so we will not spend much time on them.

Lemme Sum Up

An ATX case will give you the best combination of flexibility and affordability, since ATX motherboards are roomy and ubiquitous. Of the typical ATX case sizes, I think mid-tower is the best for most people. You can fit a hell of a lot of PC into a mid-tower case, but there are always larger cases (and motherboard form factors) if you’re one of the rare folks for whom that’s not enough.

If you’re building a new PC, now is the perfect time to explore smaller cases. A micro-ATX case is fine for a build that only needs a couple of expansion cards, and if you absolutely know you only need zero or one expansion cards and a couple of hard drives, mini-ITX is a great way to save space.

By now you should have a pretty good idea of what size and form factor to look for in a case. Next time, we’ll talk about specific features. Stay tuned, space cadets! Any questions? Use cases I missed? Post away in the comments!