Disconnect rear fan cable and remove the rear fan bracket assembly by lifting it off the system board.
Carefully take note of the location of all cable connections on the system board and disconnect all cables.
Take note of the location of the memory modules and remove them from the failing system board. See "System board diagram".
Loosen the two captured screws that secure the heat sink clamps 2. Pivot the clamps to the side to allow the heat sink 1 to be removed.
Remove the heat sink from the microprocessor by gently twisting the heat sink to break the seal formed by the thermal grease and lifting it straight up.
Place the heat sink on its side on a clean work surface so that the thermal grease is not contaminated.
Use the handle at the rear of the system board to pull the system board and tray out the rear of the chassis.
If you are replacing the microprocessor, see "Microprocessor removal and installation". Note: Do not install the heatsink until the new system board has been installed.
Install the new system board and tray into the rear of the chassis until it is fully seated.