Dell OptiPlex 5090 Tower Service Manual page 64

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 (#6-32) screw to secure the system board to the chassis.
3. Replace the eight screws (#6-32) that secure the system board to the chassis.
64 Removing and installing components