Attention
Do not open your computer or attempt any repair before reading and understanding the "Important safety information" in the ThinkCentre Safety and Warranty Guide that came with your computer. To obtain a copy of the ThinkCentre Safety and Warranty Guide, go to the Lenovo Support Website.

This section provides instructions on how to replace the heat sink.

CAUTION:

The heat sink might be very hot. Turn off the computer and wait three to five minutes to let the computer cool before opening the computer cover.

To replace the heat sink, do the following:

1. Turn off the computer and disconnect all power cords from electrical outlets.
2. Open the computer cover. See "Opening the computer cover".
3. Pivot the optical drive bay assembly upward.
4. Remove the hard disk drive to access the heat sink. See "Replacing the hard disk drive".
5. Carefully remove the four screws (1) that secure the heat sink to the system board.
   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.

6. Carefully lift the heat sink off the system board.
   Notes:
   1. You might have to gently twist the heat sink to free it from the microprocessor.
   2. Do not touch the thermal grease while handling the heat sink.
7. Position the new heat sink on the system board so that the four screws are aligned with the holes on the system board.
8. Alternate tightening each screw a small and equal amount until the heat sink is secured to the system board. Do not over-tighten the screws.
9. Go to "Completing the parts replacement".