Dell XPS 730 (Late 2008) - Manual (Page 94)

92 Replacing the Power Supply
12 Replace the four screws that secure the power supply to the back of the
computer chassis.
13 Reconnect the power supply harness to the power supply.
14 Replace the two hard drive bays.
15 Replace all hard drives installed in the interior hard drive bays (see
"Replacing a Hard Drive" on page 43).
16 Replace the hard drive fan, if applicable (see "Replacing the Hard Drive
Fan" on page 80).
17 Reconnect each of the DC power cables that were previously connected,
carefully rerouting them as you found them.
18 Replace the computer cover (see "Replacing the Computer Cover" on
page 17).
19 Connect your computer and devices to electrical outlets, and then turn
them on.