Accessing the Computer's Internals

First, let's look at the motherboard. (Note: The term motherboard may be interchanged with the term system board.)

The design of the Dell computers in our lab facilitates the quick removal of the components. Because of the wear these systems receive from constant disassembly and reassembly, removal of some components may have become more difficult with time, but you shouldn't have to force anything. Our lab PCs are tower machines that require being laid on their sides for easier access to the components. The side with the small, plastic "feet" is the side that you should be laying the machine down on. These instructions assume that the machine is already on its side.

Verify that your computer is turned off.
If the monitor has been placed on the case, please move it from the top of the machine so that you can remove the cover.
Verify that the flap on the front of the PC that hides the USB and headphone jacks is closed.
There are two buttons, one on either side of the cover toward the back of the machine. They are dark gray and shaped like a badly drawn 'D'. Press these buttons simultaneously and lift the back of the cover up and forward. Lifting the cover may be difficult and require two people, one to lift and the other to hold down the base of the machine. The cover is hinged at the front and should lift to almost a right angle with the base of the PC. Lift the lid slowly to avoid tearing the delicate connections and cables connecting the motherboard to the components mounted to the front of the machine.
Power Supply -- In the past, the power supplies needed to be removed in order to gain access to the motherboard. In the GX280's that we are using now, the power supply is small enough that this is unnecessary. If, however, you should need to remove one for replacement, unplug the machine, remove the two screws holding the supply in the case, press the green tab where the supply rests on the case, and slip the supply up and out. This is shown in the figure to the right. (Source: Dell Documentation -- Higher Education, "Dell™ OptiPlex™ GX240 Service Manual")
CDROM and hard drive bays -- The CDROM, the hard drive, and the floppy disk drive can be easily accessed from their position in the front cover (the cover that you flipped forward). If you look at any of these devices, you should see two green tabs, one on either side of each device. By grabbing the tabs of one of the devices, squeezing them toward each other, then pulling the tabs out, the device should slide from its position within the case. Try this with one or two of the devices to make sure that you can do it.

Motherboard Jumpers

Image showing jumper connecting two pins. A jumper, the blue block in the image shown to the right, is used to straddle two pins on a circuit board to create a "short circuit" or electrical connection. The outside of the jumper is plastic, but a metal strip inside of the plastic connects the two pins electrically. The processor can sense this connection (or lack of) using its binary inputs.

In the old days, the majority of a computer's configuration, everything from the amount of memory installed to the number of communication ports, was configured with a device known as a jumper. Now everything is configured using the boot configuration screen which we will discuss in the next section. There is still one thing that we need to configure with a jumper.

These electrical connections between certain pins can be used to configure some of the most basic settings of the motherboard. In earlier generations of motherboards for example, if the processor was changed, the motherboard must alter the clock frequency that drives that processor. There were jumpers on the motherboard to do that.

The only jumper still on today's motherboards is a jumper that disables the BIOS password, the password that is required to configure the PC. If the user forgets the password used to configure the PC, then the configuration will never be able to be altered again. This jumper allows the password to be reset or disabled.

Looking down on the top of your motherboard (the dark green board that is mounted to the bottom of the case you've just opened), you should a bundle of colored wires going into a plug toward the front of the board near the power supply. Next to this bundle of wires you should see a small jumper, typically black, blue, or green. If this jumper is connected, the password feature can be enable. If the jumper is disconnected, the password feature is disabled.

Verify that the PSWD (password feature) is disabled. To do this, remove the jumper and slide it back on so that only one pin goes into the jumper. This will disable the setup password but keep the jumper with the motherboard so it doesn't become lost.