Dell GX620 - 3.6GHz Desktop 1GB RAM 80GB Windows XP SFF User Manual page 146

Slide the power supply toward the front of the computer by approximately 1 inch.
6
Lift the power supply up and out of the computer.
7
Slide the replacement power supply into place.
8
Replace the screws that secure the power supply to the back of the computer chassis.
9
Reconnect the DC power cables.
10
146
1 2
1 release button
2 power supply
3 screws (2)
4 AC power connector
3
4