Dell Dimension XPS T___ - Manual (Page 14)

To remove the computer cover and support beam from a desktop or mini tower system, perform the following steps:
1. If you are working on a mini tower system, lay the computer on its right side with the chassis foot off the edge of the work surface to allow the
computer to lay flat as shown in the illustration above.
2. Loosen the cover-mounting thumbscrew that secures the cover to the back of the computer.
3. Face the front of the chassis. Use your thumbs to press in both cover release latches while pushing the cover backward. Move the cover
back about an inch, and then lift it straight up off the chassis. If necessary, use both hands and work one side at a time.
4. Pull up the front end of the support beam until the front end snaps free from its fastener. Lift the front of the beam until the hinged tabs on the
back end of the beam clear their slots as shown below.
1 Cover-mounting thumbscrew
2 Chassis foot
3 Cover release latches (2)
NOTE: The thumbscrew is captive and stays in the cover when loosened.
CAUTION: To prevent cuts, keep your hands clear of the metal edges on the chassis and fan guard as you slide the cover
back.
1 Lock tab
2 Fastener
3 Support beam
4 Slots (2)