Lenovo THINKCENTRE 2491 Hardware Maintenance Manual page 95

To replace the system fan 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. 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 tabs and then pivot the system board to release it from the chassis.
Figure 25. Releasing the system board
5. Place the system board on a clean and flat surface.
6. Remove the two rubber mounts from the system fan assembly that connect to the chassis by breaking
or cutting them with a pair of scissors. Once this has been done, remove the rubber mounts from
the rear of the chassis.
Note: When you receive your new system fan assembly, you will receive new rubber mounts.
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Chapter 8 Replacing FRUs
89