So — I’ve got my CPU, and it seems like a winner. What’s next? The obvious choice seems to be motherboard, since the processor determines to some extent what my options are there (I need a mobo that supports an Intel socket 775 chip). But I’m going to choose another component to research first, because…well, because I already bought it. Have I mentioned my poor impulse control?

When I went to the LAN party last month, I was intrigued by the variety of cases users had brought with them. There were big PC cases (REALLY big), there were small PC cases, there was even a Mac. Some had basic case mods going on (neon lights, side panel windows, etc.), and one even had a water cooling system. I liked the small boxes that looked more like cubes than towers. I thought it would be cool to build a small gaming box to bring to LANs. Bringing my Dell Dimension 4400 wasn’t that big a deal (I had a duffle bag with a shoulder strap that it fit into nicely), but how cool would it be to have one of those nice, small boxes with a built in carrying handle?

I began to research cases, and quickly realized that — as with most things PC — case choice is more complicated than it might seem initially. Fortunately, Computer Power User and Maximum PC magazines had spotlight articles on cases (or “enclosures”) in their March and April issues. (These are fine, fine magazines for the DIYer, by the way. Very highly recommended.) Based on their reviews of about a dozen cases and some of my own Internet research, here are the important things to look for when considering cases:

• form factor
• cooling considerations
• noise levels
• features
• construction quality
• aesthetics

First, there is form factor. Form factor describes the type and size of motherboard that will fit into the case. PC motherboards come in a variety of form factors: AT, ATX, microATX, BTX, and others. Specific CPUs will only work with certain motherboards, so depending on which CPU you’re using, you may be limited to certain motherboard types and, by extension, particular case form factors.

Your standard PCs — the beige or black rectangles that we’ve all come to know and disregard — are usually in the ATX form factor, the most popular form factor in use today. ATX motherboards are approximately 12” x 10”, and are usually housed in cases in either the “tower” (vertical) or “desktop” (horizontal) configurations. There are mid-tower cases (this is what you get when you buy a standard PC from Dell, Gateway, or one of the other big manufacturers) and full-tower cases (sometimes used for server computers or by enthusiasts who like a lot of room for expansion).

The small, cube-like cases that I had admired at the LAN usually support what is known as the microATX form factor, which is a slightly smaller version of the full ATX design. So, if smaller designs allow for smaller cases and less weight to carry around, why go bigger? There are a few compelling reasons:

1. ATX supports more expansion slots for video, audio, network, and other card types (a typical ATX board has 5 or more expansion slots, while a microATX supports up to 4 but more commonly 3 slots.
2. Room to work. MicroATX boards and cases are by their nature more cramped, and it can be a challenge to place your components on the board and run the necessary cables to them without mangling your hands.
3. Ventilation. ATX cases have more open space in them, and therefore are usually better at moving air around the components that need it.
4. Not all motherboards come in microATX format.

As much as I liked the idea of having a smaller PC, I eventually decided against it for the reasons above. #4 was the real killer, as the motherboard that I’m leaning toward buying doesn’t come in the microATX form factor. I also have to admit that having more room to work is very appealing, as the last computer I built was in a smallish mid-tower case and was a pain in the neck to work with.

Cooling considerations must also be taken into account. If you spend any amount of time reading BIY or overclocking sites, you learn by heart the mantra “heat is your system’s worst enemy.” Since I plan to overclock my system, I wanted to be sure to buy a case that would provide plenty of cooling options. Things to look for in terms of cooling are:

• Space and airflow design. A lot of stuff gets crammed into a case: Motherboard, expansion cards, power supplies, hard drives, optical drives, etc. Add the wiring needed to hook all this together and you can easily end up with a rat’s nest inside your box. All this stuff gets in the way of proper air flow. Ideally, air should flow into the case in the front (usually helped by an intake fan or fans mounted near the bottom front of the case), travel over the motherboard and major components, and flow out of the case at the back (with the help of one or more exhaust fans). If you don’t have adequate space in your box, all the components and wiring can get in the way and disrupt this flow, leading to a buildup of heat. Extra space is also needed if you plan to use a built-in water cooling unit in your case. And if fans aren’t place properly for optimum airflow, you can end up with “dead air” zones inside the computer (I’ve seen cases with input and output fans located right next to each other — not an optimal plan for circulating air around the whole case).
• Fans. Fans help pull cool air into your case and exhaust hot air out of it. At a bare minimum, a case will usually have two exhaust fans: one built into the power supply and one at the back of the case in the area the CPU will reside (this is how my Dell is set up). This is not adequate for a mid- to high-end gaming box, however. You want to be sure that your box has at least one input fan (usually at the front of the case) and one or two exhaust fans in addition to the power supply fan. Having both input and exhaust fans will insure that there is a constant flow of air over your motherboard and other components. Some enthusiast-level cases come with up to five input and five exhaust fans.
• Cable routers. The mass of cables that collect inside a case can block air flow. A well-designed case will include a cable routing system that helps to organize cables and keep them out of the way.

Next time, we’ll look at the other important case design considerations (noise, features, construction and aesthetics) and see how well the case I bought — the Gigabyte 3D Aurora 570 — stacks up.