HP EliteDesk 800 G1 Tower Service Manual page 105

6.
Slide the board toward the side of the chassis to disengage it from the system board connector ,
and then lift the extension board from the chassis (2).
7. Remove the eight Torx T15 screws (1) that secure the system board to the chassis.
8.
Slide the system board toward the front of the computer to disengage the I/O panel, and then lift
the system board out of the computer (2).
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 and PCI expansion slot daughter card
93