Before you can examine the computer's internal components, you must open the case. There is no universal method for removing the cover because every manufacturer uses a somewhat different design. Computer case design is a compromise between appearance and function; the ideal cabinet looks good from any angle, but it's also easy to open and close.
If you're lucky, the owner's manual or other documentation supplied with the computer includes a detailed set of instructions for removing the cover, or there's a Web site with a short video or a step-by-step procedure. If not, you have to spend some time examining the computer in order to find the secret. Even if it's not immediately obvious, there is always a way to open the case-if there wasn't, the people who assembled the computer wouldn't have been able to install the parts inside the box.
Before you open a computer case, you should take some precautions to avoid injuring yourself or damaging the components inside the case.
First, be sure to either unplug the power cable or turn off the switch on the back of the case before you remove the cover. Some components inside the computer remain "on," even when the computer is "off"-that's why you might see a lighted LED indicator on a motherboard when the computer is not running.
Second, don't try to open up the power supply or poke around inside it with a screwdriver or other tool; some of the components inside the power supply enclosure carry extremely high voltages that can cause injuries or even fatal shocks,
Next, ground yourself to prevent shocks caused by static electricity before you handle any components inside the case, with or without tools. Even if you can't feel a static shock, it can be powerful enough to damage internal parts. At an absolute minimum, place your hand on a metal part of the case before you touch a circuit board or other component. If possible, use an anti-static wrist strap or similar grounding system (available from electronics supply retailers) every time you open a computer case or handle other electronic components.
Finally, you can often save a lot of time and prevent confusion by taking some photos or making detailed drawings of the equipment inside the case and the individual jumper and switch settings on various parts, before you remove them. This makes it much easier to reassemble the computer and restore the original settings after you have finished your work.
Most cases use either sheet metal screws, thumbscrews, or some kind of latching mechanism to hold the cover to the case. The screws or latches are most often located on the back of the case, but sometimes you might find one at the front of a desktop case or on the side of a tower. If the case uses sheet-metal screws, you need either a screwdriver or a 1/4-inch nut driver to remove them.
As you remove screws from the case, place them all in a little bowl where you can find them easily when you're ready to reassemble the computer.
Figure 4.1 shows common locations of the screws or latches that hold a tower case together. If the side of the case does not come loose after you remove the screws, try sliding it toward the back of the computer; sometimes there are sheet-metal tabs holding the side to the rest of the case. Move the side panel an inch or less and then lift up.
Figure 4.1: Look for screws or latches at the back and side of a tower case.
If the side of the case doesn't budge, take a close look at the front of the computer. In some designs, one or more screws are not visible or accessible until you remove the front panel.
Most tower cases mount the motherboard on the right side of the case (looking at the front), so the piece to remove to examine the other components inside the computer is usually the left side panel. But it's inevitable that somebody, somewhere in the world makes a tower case that opens from the right. If you can't open the case from one side, or if you see nothing but a mounting tray or the bottom of a big printed circuit when you remove the side panel, try the opposite side.
Still other tower cases use a U-shaped cover that lifts upward off the cabinet. To remove a U-shaped cover, lift it up and away from the rest of the computer.
The screws or latches that hold the cover to a desktop case are almost always located at the back of the case. Some case covers are flat panels attached to the top of the box, and others are bent sheet metal that cover the computer's top and sides. To open the case, remove the screws and slide the top toward the back or lift it straight up.