Dell Dimension 3100C - Manual (Page 43)

6. Slide the power supply toward the front of the computer by approximately 1 inch.
7. Lift the power supply up and out of the computer.
8. Slide the replacement power supply into place.
9. Replace the screws that secure the power supply to the back of the computer chassis.
10. Reconnect the DC power cables.
11. Replace the CD/DVD drive.
12. Connect the AC power cable to the connector.
13. Replace the computer cover.
DC Power Connectors
1 release button
2 power supply
3 screws (2)
4 AC power connector