Lenovo ThinkStation 4215 Hardware Maintenance Manual page 106

To replace the heat sink and fan assembly, do the following:
Figure 21. Removing the heat sink and fan assembly
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Hardware Maintenance Manual
1. Remove all media from the drives and turn off all attached devices and the
computer. Then, disconnect all power cords from electrical outlets and
disconnect all cables that are connected to the computer.
2. Remove the computer cover. See "Removing the computer cover" on page 87.
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 86.
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 86.
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 1 , then fully remove screw 2 , and then fully
remove screw 1 .
b. Partially remove screw 3 , then fully remove screw 4 , and then fully
remove screw 3 .
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.
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.