HP Compaq dc7100 DT Reference Manual page 179

11. Slide the system board tray assembly towards the front of the chassis, about 7 mm (1/4-inch)
and lift the system board up and out of the computer.
12. Remove the three screws 1 that secure the backwall assembly to the chassis, then slide the
backwall assembly 2 a few millimeters/inches toward the space vacated by the power supply
and lift out.
Service Reference Guide, dc7100
Removal and Replacement Procedures— Small Form Factor (SFF) Chassis
361288-003 7–53