Dell XPS 720 (Mid 2007) - Manual (Page 152)

152
Removing and Installing Parts
7 Remove the hard drive bays from the chassis.
8 Remove the four screws that attach the power supply to the back of the computer chassis.
9 Gather the power supply bundles that stem from the power supply, for easy removal.
1 screws (4) 2 hard-drive bays
1 2