Power supply 
support bracket 
Power supply release tab
10.Raise the power-supply cage slightly and press and hold the release tab on the rear power-supply support bracket; then, lower the power-supply structure into position. For clarity, the power-supply cage is not shown in the illustration.
Rear fan assembly with baffle
11.Install the rear fan and fan structure on the chassis:
a.Align the clips on the rear fan assembly with the holes in the chassis.
b.Slide the assembly toward the power-supply cage until it stops.
22IBM System x3500 Type 7977: Installation Guide
