Dell XPS 730 (Late 2008) - Manual (Page 92)

90 Replacing the Power Supply
7 Remove the four screws that attach the power supply to the back of the
computer chassis.
8 Disconnect the power supply harness from the power supply by depressing
the two tabs and pulling the harness away from the power supply.
1 screws (4) 2 hard drive bays
1
2