Lenovo ThinkCentre M91p 4524 Hardware Maintenance Manual page 104

2. Remove the computer cover. See "Removing the computer cover" on page 79.
3. Lay the computer on its side for easier access to the system board.
4. Locate the heat sink and fan assembly. See "Locating parts on the system board" on page 77.
5. Disconnect the heat sink and fan assembly cable from the microprocessor fan connector on the system
board. See "Locating parts on the system board" on page 77.
6. Follow this sequence to remove the four screws that secure the heat sink and fan assembly to the
system board:
a. Partially remove screw
b. Partially remove screw
Note: Carefully remove the four screws from the system board to avoid any possible damage to the
system board. The four screws cannot be removed from the heat sink and fan assembly.
Figure 28. Removing the heat sink and fan assembly
7. Lift the failing heat sink and fan assembly off the system board.
Notes:
a. You might have to gently twist the heat sink and fan assembly to free it from the microprocessor.
b. Do not touch the thermal grease while handling the heat sink and fan assembly.
8. Position the new heat sink and fan assembly on the system board so that the four screws are aligned
with the holes on the system board.
Note: Position the new heat sink and fan assembly so that the heat sink and fan assembly cable is
toward the microprocessor fan connector on the system board.
9. Follow the following sequence to install the four screws to secure the new heat sink and fan assembly.
Do not over-tighten the screws.
a. Partially tighten screw
b. Partially tighten screw
96
ThinkCentre Hardware Maintenance Manual
1 , then fully remove screw
3
, then fully remove screw
1
, then fully tighten screw
3 , then fully tighten screw
2 , and then fully remove screw
4
, and then fully remove screw
2
, and then fully tighten screw
4 , and then fully tighten screw
1 .
3
.
1
.
3 .