HP EliteDesk 800 G4 SFF Maintenance And Service Manual page 71

8. Slide the system board toward the front of the computer to disengage the I/O panel (1), then lift the rear
of the system board upward (2), and then pull it out of the computer (3).
When reinstalling the system board, first insert the I/O panel back into the slots in the rear of the chassis, and
then align the board with the chassis screw holes.
NOTE: When replacing the system board, you must change the chassis serial number in the BIOS.
System board 63