Dell OptiPlex 3050 Small Form Factor Owner's Manual page 32

d Data cable [4]
5 Disconnect the following cables and screw from the system board:
a PSU [1]
b hard drive and optical drive caddy stand off screw [2]
c PSU [3]
d System fan [4]
e power switch [5]
f intrusion switch [6]
32 Removing and installing components