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Choosing the Perfect Case

Choosing the Perfect Case

Whether you're building your own PC from the ground up, out shopping for a new system, or planning to upgrade an existing system, a case (also called a chassis or an enclosure) is far more than "the box the computer parts come in." In fact, choosing the right case design can make your system building and upgrading easier, while the wrong case will doom you to limited expandability (not to mention a few sore and cut fingers!).

It's Time for These to Go - Baby-AT and LPX

Since the first IBM PC was introduced twenty years ago, there have been many case and motherboard designs (form factors) which have passed into history. It's time for two more, which you may have, to do the same:


If your case contains a Baby-AT motherboard, whether it's a mid-tower, full-tower, desktop, or "pizza-box" slimline model, it's time to bid it farewell. It's getting very difficult to find motherboards in the Baby-AT form factor, and those that are still around typically don't support the latest CPU or memory technologies. If your case resembles the one shown here, plan to buy a new case as part of your next upgrade project.

Figure 1

Figure 1 - A Baby-AT case - once the industry standard but now obsolete

Another case design that it's time to put aside is LPX. LPX cases vary a great deal. Most are slimline desktops, however, they can be mid-size towers about the size of the previous figure, mini-towers, or desktop cases, but they all use some type of a riser card that fits in the middle of the motherboard. The riser card is used for the expansion slots. The lack of standards for LPX means it's not upgradeable at a motherboard level.

Figure 2

Figure 2 - One variation on the many flavors of the LPX motherboard, this old Packard-Bell motherboard/riser card places add-on cards parallel to the motherboard.

Figure 3

Figure 3 - Another variation on LPX uses a T-shaped riser card to mount cards at their normal 90-degree angle to the motherboard, but about 1.5" above it.

The Current Players in the Case Game

There are five current case types that work with today's case designs:

    NLX Slimline
    ATX Desktop
    ATX Mini-tower
    ATX Mid-size tower
    ATX Full-size tower

PCs on Your Desk - Slimline and Desktop Case Designs

Both desktop and slimline cases can fit on your desk, but slimline cases are shorter top-to-bottom, earning them the nickname of "pizza box."

Slimline cases greatly restrict your expandability (3 drive bays are typical), and must use a riser card for slot expansion, as the cases are too short for cards to be plugged directly into the motherboard. Because of the riser card requirement, most slimline cases today use NLX motherboards, and have riser cards offering only two or three expansion slots. Stay away from slimline cases that use LPX boards, as there is little standardization or interchangeability.

Desktop cases are larger, and can offer from five to seven drive bays. A desktop case is basically the same thing as a mid-tower case sitting sideways. There are even cases that can be used both ways, featuring a drive cage that can be rotated 90 degrees. Since they are based on mid-tower designs, desktop cases normally accept full size ATX boards, which means they can also take micro-ATX or flex-ATX as well. See the comparison sketch in Figure 4.

Figure 4

Figure 4 - Both slimline (top) and desktop cases (bottom) can fit on your desk, but slimline cases also make for slim upgrade options.

While desktop cases can provide expansion options comparable to mid-size tower cases, the bulky box needed to hold larger motherboards and five or more drives takes up a lot of desktop space. One advantage is it keeps the frequently accessed drives right in front of you, which is nice if you burn a lot of CDs or use other removable media extensively. If you really want to try a desktop case, but want to keep your options open, look for a model which is convertible into a tower case.

Deskside Skyscrapers - Tower Cases

Tower cases were once used only by servers, but are now the most popular choice for most systems. However, just because a case is called a "tower" case doesn't mean it has adequate expansion capacity for the future. Compare the mini-tower used by many low-cost retail store systems like those from Hewlett-Packard or Compaq to a typical mid-tower case.

The HP and Compaq cases have only three drive bays and can use only Micro-ATX motherboards with a maximum of four slots. Most use very low wattage SFX (small form factor) power supplies as well. These systems are almost as limited in expandability as a typical slimline system (see Figure 5)

Figure 5

Figure 5 - A typical mini-tower case gets the computer off your desktop, but is almost as cramped inside as a slimline computer.

Most users are much better served by a mid-tower case, typical of "white-box" (generic) PCs sold by various suppliers, such as the one shown in Figure 6 Similar cases are used by major PC vendors as well for the mid-range and high-range PCs.

Figure 6

Figure 6 - Five to six total drive bays and room for full-size expansion slots make mid-tower cases a good option for most users.

This case can hold ATX, Micro-ATX, or flex-ATX motherboards and has room for three 3.5" and three 5.25" drives. For ease of mounting, the 3.5" drive bay assembly snaps out of the case.

If you need to support seven or more drives then get a full-tower case, but be prepared to pay for the extra drive bays and extra-large power supply needed to provide adequate power for such a case.

Safety and Durability Features To Look For

Beyond the obvious (number and types of drive bays and motherboard types supported), consider these features:

Make sure that the case you choose has a high-quality UL approved power supply. Many cheap cases are bundled with unapproved power supplies which can be dangerous to both you and your components. Also note that UL approval only covers safety and indicates nothing about the stability, reliability, regulation, or accuracy of the output. There are many so-called 250-watt supplies that don't really put out 250 watts of sustained clean DC power. For a mid-tower, I recommend at least a 250 to 300 watt power supply, even larger if you are using the higher speed processors or more than 3 drives. Look for name brand power supplies like those from PC Power and Cooling, Astec, or others.

Handy Options

If you do a lot of work with hot-swapped USB components like digital cameras, look for cases with USB ports in the front of the case. These can save you a long reach around to the rear of the case. Most newer motherboards feature an on-board connector which is designed to be connected to the front panel USB ports via a small ribbon cable.

If you plan to install several removable-media drives, make sure that the drive bays you want to use are externally accessible. It costs a bit more to have front case openings, so some cases may have a lot of drive bays but not grant you access to all of them.

Round-top cases may look "cool" in your work area or at home, but if you like to place SuperDisk (or Zip) drives, USB hubs, external modems, terminal units, routers, or network switches and hubs atop your PC, skip cases with this feature.

If you plan to change motherboards once or twice during the life of your case, look for a model with a lift-out motherboard tray.

If you swap or add cards frequently, get a model with a removable side cover that doesn't require a complete case disassembly.

You'll find a huge number of case and chassis vendors out there, but here are a few of the best:

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