HP Pavilion xt800 - Desktop PC Manual page 6

4 Loosen the two thumb screws on the right
side of the back panel. The first time you
loosen these screws you'll need a flathead
screwdriver. (These screws do not detach;
they'll stay on the side panel loosely until
you tighten them again.)
5 Stand behind the computer, and place one
hand on top of the chassis.
6 Grasp the handle (A) with your other hand
and pull the panel towards you until it
stops.
7 Lift the panel up and out. Set the panel
aside.