Cases and Power Supplies
Cases
A computer's case is more than a box. The case includes the drive cage, the internal compartment that holds disk drives, and almost always the power supply, among other features, all of which we discuss in this chapter. As discussed in Chapter 3, "Motherboards and Their Components," cases come in various types called form factors, which differ in layout of components. The case's form factor needs to match that of the motherboard and the power supply. Just as with motherboards, some cases are proprietary and require proprietary power supplies and motherboards.
Case Components
Cases come with various components, as shown in Figure 4.1.
Figure 4.1: A typical ATX case.
Most of these components are self-explanatory. Drive bays are areas in the front for installation of removable media (CD, DVD, floppy, Zip, etc.). The 5 1/4-inch bays are for all but the floppy drives. Cases usually come with small speakers, which are there to provide very basic sounds to the user. About all these speakers play are warning beeps and the sound of a modem connecting. These speakers are very important, because multimedia speakers don't work before Windows has booted, if Windows is in Safe Mode (see Chapter 2, "System Configuration and Computer Hygiene"), or if there is a problem with the sound card.
Note Some motherboards have extremely small speakers soldered onto the board. These are little black plastic cylinders with a hole at the top. These boards don't use case speakers.
While many older PCs had key locks, few newer ones do. Locking a computer prevents it from being powered on. The most important indicator lights are the ones that show that power is on and that the main hard drive is active. The hard drive indicator is helpful to show if the hard drive is running too much (churning), or if the computer is locked up (the light does not go on even though the computer is running). On recent cases, the only button is the power button. Older cases might have a Reset button, which simply turns power off and on, and a "Turbo" button. Leave the Turbo button in the On position unless a tech support technician tells you to turn it off.
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