Dell Latitude D620 ATG - Manual (Page 36)

17. Remove the four 5-mm hex screws on the back of the computer.
18. Lift the system board out and away from the base.
Installing the System Board
1. Perform all the steps in Removing the System Board in reverse order.
1 fan
cable
2 M2.5 x 5-mm screws (4) (identified by silver
triangles on the system board)
3 modem antenna
connectors (2)
1 system board 2 base
NOTICE: When installing the system board, ensure that the fan cable and antenna cables are clear of the system board before fitting it into the base,
that the audio connectors are properly seated, and that the tab for the wireless switch fits properly into the detent on the slider mechanism before
installing the system board into the base.