Follow this sequence to remove the heat sink from the system board:
Partially remove screw (1), then fully remove screw (2), and fully remove screw (1).
Partially remove screw (3), then fully remove screw (4), and fully remove screw (3).
Carefully lift the heat sink off of the system board.
Remove the plastic cover from the bottom of the new heat sink to expose the heat sink grease (this cover protects the heat sink grease from contamination). Notes:
Do not remove the plastic cover until you are ready to install the heat sink and fan assembly on the microprocessor. Do not touch the grease on the heat sink and fan assembly. Do not put the heat sink and fan assembly anywhere except on the microprocessor after the plastic cover has been removed and the grease exposed.
Some heat sink part numbers will have orientation labels showing "Front of System." Heat Sinks that do not have orientation labels should be oriented so the fan cable is toward the board connector labeled "CPU Fan."
Place the new heat sink into position. Important: Do not touch the thermal grease while handling the heat sink.
Align the four screws on the heat sink with the four mounting studs in the chassis.
Follow this sequence to install the screws, noting that fully tight is 5 in-lbs +/- 0.5 in-lbs:
Partially tighten screw (1), then fully tighten screw (2), and fully tighten screw (1).
Partially tighten screw (3), then fully tighten screw (4), and fully tighten screw (3).