Dell OptiPlex 7080 Tower Service Manual page 91

Steps
1. Slide the front I/O-ports on the system board into the front I/O-slots on the chassis and align the screw holes on the system board
with the screw holes on the chassis.
2. Replace the screw (M2x4) that secures the system board to the chassis.
3. Replace the eight screws (#6-32) that secure the system board to the chassis.
Disassembly and reassembly 91