Lenovo ThinkCentre 3512 Manual page 98

the Safety , Warranty, and Setup Guide, go to:
http://www.lenovo.com/support
This section provides instructions on how to replace the heat sink assembly.
CAUTION:
The heat sink and fan assembly might be very hot. Turn off the computer and wait three to five
minutes to let the computer cool before removing the computer cover.
To replace the heat sink assembly, do the following:
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. Place a soft, clean towel or cloth on the desk or other flat surface. Hold the sides of your computer and
gently lay it down so that the screen is against the surface and the cover is facing up.
3. Remove the computer cover. See "Removing the computer cover" on page 81.
4. Locate the heat sink assembly on the system board. See "Locating major FRUs and CRUs" on page 68.
5. Remove the system board shield. See "Removing and reinstalling the system board shield" on page 88.
6. Follow the sequence
heat sink assembly to the system board.
Note: Carefully loose 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 assembly.
Figure 27. Loosing the four screws that secure the heat sink assembly to the system board
7. Lift the failing heat sink assembly off the system board.
Notes:
a. You might have to gently twist the heat sink assembly to free it from the microprocessor.
b. Do not touch the thermal grease while handling the heat sink assembly.
8. To reinstall the heat sink assembly, position the new heat sink assembly on the system board so that the
four screws are aligned with the corresponding holes in the system board.
92
ThinkCentre Hardware Maintenance Manual
1 , 2 , 3 , 4 on the heat sink assembly to loose the four screws that secure the