Lenovo THINKCENTRE 2491 Hardware Maintenance Manual page 89

This section provides instructions on how to replace the microprocessor.
CAUTION:
The heat sink and microprocessor 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 microprocessor, 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. Open the computer cover. See "Opening the computer cover" on page 72.
3. Locate the system board and disconnect all cables connected to the system board. See "Locating
parts on the system board" on page 71.
4. Press inward on the two side tabs and then pivot the system board to release it from the chassis.
Figure 19. Releasing the system board
5. Place the system board on a clean and flat surface.
6. Remove the heat sink. See "Replacing the heat sink" on page 81.
Note: Place the heat sink on its side so that the thermal grease on the bottom of it does not get in
contact with anything.
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Chapter 8 Replacing FRUs
83