Desktop PCs come in many different shapes and sizes, so opening them requires a different strategy depending on the model you own. In order to open the Dell Dimension models, work on a flat surface with a lot of space. This article deals with the 3000, 8400, and 5100 models. Also take note of the preliminary instructions to ensure safety from electrical shock.
Click "Start," "Turn Off Computer," "Turn Off."
Disconnect any Ethernet or phone cables from the computer.
Disconnect all cables, including the power cable. Then, press the power button (this grounds the motherboard).
On a flat surface, lay the computer on its side, with the cover on top. The cover side of the computer is closest to the fan, whereas the other side is closest to the power switch and plug.
If your computer cover has a cover latch, slide and hold the cover latch.
On the back of the cover there should be small indents. Grab these, and gently lift to take off the cover.
Slide the cover towards the back of the computer.
Lay the computer on its side. Make sure the arrow on the bottom of the computer is facing up (see the Resources section for a picture).
There will two release buttons on the top and bottom of the computer. Press and hold them both.
Lift the cover up and away, as you would when you open a laptop.
Lay the computer on its side.
On the top panel of the cover, pull back the cover latch release.
Lift the cover up and away, and place it on a flat surface.