Dell Precision Tower 3420 Owner's Manual

Removing the power supply unit (PSU)

1. Follow the procedure in Before Working Inside Your Computer.
2. Remove:
   1. cover
   2. front bezel
   3. hard drive
   4. optical drive
   5. heatsink fan cover
3. To release the PSU:
   1. Disconnect the power cable from the system board [1, 2].
   2. Unroute the power cables from the retention clips on the chassis [3}.
   
4. To remove the PSU:
   1. Remove the screws at the back of the computer that secure the PSU to the computer [1].
   2. Press the blue release tab [2] and lift the PSU away from the computer [3].