Holding the Drives: Drive Bays

Internal drive bays

Just about every personal computer has at least one hard drive inside the case, and many include two or more. After a hard drive has been installed, there is no reason to remove it unless the drive fails or you replace it with a larger drive. Because it's not necessary to provide physical access to a hard drive during normal operation of the computer, the drive bays may be located deep inside the case.

So the internal drive bays can be just about anywhere : front, back, middle, at the top of the case or near the bottom. As long as the cables can reach the motherboard and the power supply, it doesn't make any difference. One of the challenges of designing a computer case is finding space for at least two or three hard drives without increasing the size of the case any more than absolutely necessary. Like Doctor Who's Tardis or Snoopy's doghouse, a computer case should be bigger on the inside than the outside.

If all the external drive bays aren't filled with drives that use removable media, it's easy enough to convert a vacant external bay to an internal drive bay by mounting a hard drive in the bay and replacing the original blank cover.

Moving Data Around: Internal Cables

The first thing you will probably notice after you open up your computer for the first time is that there are a lot of wires and cables inside, running in many directions. Fear not; there really is some kind of logic to this wiring.

There are several kinds of cables and wires inside your computer:

• Power cables that carry DC power from the power supply to the motherboard, the fans, the disk drives , and other devices. The power supply often includes enough cables and plugs to provide power to more devices than your computer currently uses, so there are often spare power cables and plugs that don't connect to anything; it makes the inside of the computer neater and easier to work with if you can use a cable wrap or even a short piece of string to tie the unused cables to a rail or some other part of the internal frame. That extra cable is useful when you want to add a new hard drive or other component to your computer.

• Data cables that move signals between the motherboard and the disk drives and other storage media.

• Audio cables that carry digital audio between the sound card (or equivalent on the motherboard) and the CD or DVD drive, and from the motherboard to the internal speaker inside the case.

• Control wires that extend switch contacts or LED indicators from the computer's front panel to the motherboard. Each of these wires has a connector at the end with a label that corresponds to a pin on the motherboard.

• Signal cables that extend data and control signals from the motherboard to connectors on the front or back of the case.