How to build your own personal computer - Kitchen Table Computers


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Choosing a Computer Case and Power Supply


It may not seem too exciting, but selecting a case for your homebuilt computer is one of the most important steps in the planning process. The case you select will determine what form factor motherboard you will need, how many drives you can install, and many other things.

It also a lot easier to assemble a computer when the case has been intelligently designed. A poorly-design computer case can make what should be a fun experience a downright miserable once.

But although the choice of a computer case is important, it's also one of the choices that can save you some money. Computer cases vary in price from about fifty bucks to several hundred dollars, but the main difference is that the higher-end cases tend to be fancier. You can get perfectly good, high-quality computer cases inexpensively if you're willing to do without, say, flashing neon lights.

Choosing a case wisely can save you many hours of annoyance and expense later on. Here are some of the things you should consider:


Form Factor

The form factor is the first thing you must consider when selecting a case for your new computer. The most common form factors as of this writing are still ATX and micro-ATX, which differ mainly in their size. They are electronically identical.

If you are planning on using a full-size ATX motherboard, then you will need a full ATX case. But a micro-ATX motherboard can be used in a full-ATX case, provided you don't mind having some empty space at the bottom of the computer.


Number of Drive Bays

Computer caseAnother important factor affecting the size of case you choose is the number of drives you plan to install. Almost all PC cases have internal bays for at least one hard drive, and front-accessible bays for at least one optical drive (CD-ROM, CD-RW, DVD-ROM, or DVD-RW) and a floppy drive.

But most people who build their own computers want more than this minimal configuration. Having two optical drives, for example, is a popular configuration, as it allows direct copying of optical media from one drive to the other (subject to copyright restrictions). Other popular options include ZIP drives, card readers, and tape drives. All of these devices occupy drive bays.

Also, as technology advances, new devices are invented that are designed to fit in existing cases. Who knows: You may want a toaster that fits in a 5.23 inch drive bay. If you don't have a drive bay available, then you'll be out of luck. So save yourself trouble in the long run by selecting a case with an adequate number of drive bays -- plus one or two extra, just in case.

If you are building a computer with many hard drives (such as a computer for multi-camera video editing, in which it's common to use separate drives for each camera, plus the system and storage drives), then you may want to consider using a server case that has lots and lots of 3.5 inch bays.

Sometimes a computer case will have a lot of 5.25 inch bays, but not enough 3.5 inch bays for the computer that you want to build. For example, you may want a floppy drive, a ZIP drive, and a 3.5 inch card reader. That's not a big problem. There are inexpensive adapters available that will allow you to install 3.5 inch drives in 5.25 inch bays.


Power Supply

Power supplies are sometimes included and pre-installed in computer cases. But sometimes a perfectly good case may come with a crappy or inadequate power supply — and the power supply is not a part you want to skimp on. A bad power supply can fry your whole system. In fact, sometimes I find a computer case that I love, but which comes with a power supply that I hate; so I just remove the included power supply and install a better one.

Make sure the power supply you use is of high quality and is adequate for your needs and has the correct connectors for the type of system you are building. I personally like power supplies from Antec, Thermaltake, and CoolerMaster. All of these companies also sell complete computer cases, and I've had excellent success with them. In fact, the computer I used to originally write this site was upgraded about a zillion times since the day it was built, but the CoolerMaster case and power supply kept going strong.

It's also important to select a power supply that can provide sufficient wattage for your system and that has the right connectors. Most power supplies today come with lots of SATA connectors, but few Molex connectors. If you're using drives or cards that need Molex but don't have enough Molex leads (or vice-versa) you'll either have to make sure the power supply has enough of what you need, or else buy some adapters.

The following are my minimum power supply recommendations based on the combined number of drives (floppy, optical, tape, and hard drives) in a Pentium D, Core2 Duo, or Athlon 64 X2 system:

  • Three drives: 400 Watts
  • Four or five drives: 500 Watts
  • Six to eight drives: 650 Watts
  • More than that: You really should consider dual power supplies.

Also remember that many USB and Firewire devices draw their power from the computer's power supply, so you'll want to leave plenty of headroom when calculating wattage requirements.



Chassis fanExcess heat is one of your computer's worst enemies. Select a case that has at least one place to mount a chassis fan. Without a chassis fan, the heat thrown by the power supply fan, CPU fan, chipset fan, and video card fan will rapidly raise the temperature inside the case. A simple case fan will help bleed this heat off and keep your computer cool and happy.

If you have pets that shed hair, or if you plan to use your computer in a dusty place, try to find filtered cooling fans. These will help keep the dust out of your system. (You'll have to clean the filters frequently, though, so they don't get clogged!)

You also may want to consider a hard drive cooler, especially if the computer will be used in a hot environment or if you need to use a small case because of space limitations in your office, dorm room, or jail cell. But too-small cases can also cause major heat buildup, which in turn can cause all sorts of errors, failures, and other problems. So keep this in mind when thinking about how perfectly that "cute, little case" would fit on your bookshelf.



Some people couldn't care less about a computer's looks. Others go to great pain to find a case that matches their decor or is otherwise pleasing to their eyes. Me, I like simple designs that look like a computer and not a jukebox.

Unlike the "old days" of computing when everything was boxy-looking and putty-colored, PC cases are now available in a full spectrum of colors, styles, and designs. Some even have transparent side panels framed with flashing neon lights. Some people, especially gamers, like the effects that these lights provide. Others (like me) think the lights are useless and a waste of energy. But hey, whatever floats your boat.

What it boils down to is that only you know how important appearance is to you. This computer you're building is your creation, so make it what you want it to be. Once you've narrowed your selection down to a few cases based upon the more important criteria listed above, it's perfectly okay to pick the case that you think is the coolest-looking of the bunch.


Ease of Assembly and Maintenance

Finally, when selecting a computer case, consider how the case design will make it more or less difficult to assemble a computer and to maintain it once it's built. Look at things such as how easy the case is to open, whether the drive cages are easily removable (which makes drive installation and replacement easier), how difficult routine cleaning and dust-removal will be, and whether you'll have room for upgrades. We're geeks, after all, so it's only a matter of time before we open the case again to do some modifications.


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