Dell Precision 3430 Small Form Factor Service Manual page 66

b Unroute the power cables from the retention clips on the chassis [2,3].
c Disconnect the PSU power cable from the connector on the system board [4].
4 To remove the PSU:
a Remove the 3 screws that secure the PSU to the system [1].
b Press the blue release tab [4] at the rear end of the PSU unit, slide the PSU and lift it away from the system [2].
66 Removing and Installing components