Your Computer's Case (continued...) 

Switches and LEDs
    If you look at the front of your case you can see the devices that are installed in the external bays and get an idea as to how many unused bays you have. You will also notice one or more switches and LED lights.

Power switch
    To start your computer, you have to turn on the power supply. At one time, the power switch for your computer was on the power supply itself, and you had to reach around to the back of your computer to turn it on and off. This was inconvenient, troublesome, and a real pain in the …neck. Most cases today have a remote power switch on the front of the case.

Reset switch
    When you first start your computer, it goes through a series of self-tests (POST - Power-On Self Test) before it actually initializes itself and starts up the operating system. The reset switch performs the same function as a warm boot (ctrl+alt+del) which restarts your computer with an abbreviated version of POST, taking a little time off the startup process. With Win95/98’s restart option on the Start menu, today’s computer cases may or may not have a reset switch.

Turbo switch
    When computer speeds started to increase dramatically, older software programs sometimes worked too fast. This was especially noticeable in games. By pushing the Turbo switch, you could slow the speed down to where these programs were still usable. This also became the number one cause for a lot of trouble calls from people complaining that their computer "just doesn’t work as fast as it used to". Most cases today don’t have a Turbo switch.

Keylock switch
    Most new cases don’t have a Keylock switch. By inserting and turning a key in this lock, you could shut off access to the keyboard, thus denying unwanted users from accessing your computer or preventing an accidental keystroke from interfering or interrupting a currently active program. These are still found on network servers.

Power LED
    This light tells you when the power is on to your computer.

Hard Drive LED
    This light will go on, or flicker, every time your hard drive is written to or read from. It lets you know whenever the hard drive is being accessed.

Turbo LED
    Not found on newer cases, the Turbo light would tell you when the Turbo switch had been pushed.

Speed LED
    The Speed Indicator LED is supposed to indicate the speed (in megahertz) that your computer runs. The problem is, they don’t actually read the speed. These LEDs have to be set using an array of jumpers in the front panel of the case. If you change the speed of your computer, these indicators won’t change unless you physically change the jumpers. Unless you have the instructions (cases don’t always come with instructions), you don’t have much of a chance at guessing the jumper configuration. There’s getting to be fewer and fewer computer cases with Speed Indicator LEDs.
   
Each device installed in a case’s external drive bay (floppy drive, CD-ROM, tape drive, etc.) will usually have it’s own indicator LED on the front bezel that will come on or flicker when that device is being accessed.
 
    The back of your computer will have holes and slots cut into the frame. These holes allow for the back of expansion cards and any I/O ports that your external devices can plug into. Any slot or hole that is empty should have a cover on it. These are easy to distinguish from any venting holes that might be on the back of your case (venting holes should not be covered). The back of the power supply will also be exposed here showing you the power supply fan vent and the plug for the power cord.

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