Apple iMac G5, 20-inch - Manual (Page 67)

iMac G5 (20-inch) Take Apart - Logic Board
7. Check again that the light pipe is in position before lowering the logic board into place
8. Important: The DIMM latches are delicate. Position the DIMM latches into the locked
position (closed) prior to installation.
9. Lower the logic board into the chassis. Caution: Do not twist, bend or flex the board
as you lower it into the chassis. Flexing the board may jeopardize the thermal interface
between the heartsink and the processor. Make sure the light pipe seats properly into
the bottom left corner and that the cables are not caught under the board.