Dell OptiPlex G1 - Manual (Page 42)

System Board Removal (Low-Profile Chassis): Dell ™ OptiPlex ™ G1 Systems
To remove the system board, follow these steps:
1. Disconnect all cables from their connectors at the back of the computer.
2.
Remove the expansion-card cage .
3. Disconnect all cables from the system board.
4. Remove the screw that secures the system board to the bottom of the chassis.
5. Slide the system board toward the front of the chassis until it stops.
6. Carefully lift the system board out of the chassis (be sure to lift evenly and not twist the system board).
When you reinstall the system board (before you slide the system board back to lock it in position), push down near each slot to engage the grounding clip onto its
corresponding tab. Push evenly on both sides of the system board as you slide it into position (do not twist the system board).
NOTES: If you are replacing the system board, remove all DIMMs, the video-memory upgrade module (if present), the single-edge contact (SEC)
cartridge/heat sink assembly, and the guide bracket assembly from the old system board and install them on the replacement board. Also, set the
jumpers on the new system board so that they are identical to those on the old board, unless a microprocessor upgrade is being installed.
If the original system board has a NIC connector, ensure that the replacement board has a NIC connector.