Lenovo C240 All-in-One - Manual (Page 40)

Step 5. Remove the 4 screws that secure the heat-sink module to the motherboard.
Step 6. Lift up the heat-sink to remove it.
Attention: Place the heat-sink upside down on a flat surface to prevent thermal grease contaminating
other components.
Step 7. To install the new heat-sink:
a. Use an alcohol pad to wipe the thermal grease off the CPU.
b. Line up the new heat-sink module with the mounting holes on the motherboard.
c. Secure the new heat-sink to the motherboard with the screws, making sure to fit the screws in
sequence following the numbers printed on the new heat-sink.
d. Use the adhesive tape to seal the gap between the heat-sink and system fan.
Step 8. Reattach the rear cover and secure it with the screws.
Replacing the system fan
Note: Turn off the computer and wait 3 to 5 minutes to let it cool down before removing the rear cover.
To replace the system fan:
Step 1. Remove any media (disks, CDs, DVDs or memory cards) from the drives, shut down the operating
system, and turn off the computer and all attached devices.
Step 2. Unplug all power cords from electrical outlets.
Step 3. Disconnect all cables attached to the computer. This includes power cords, input/output (I/O)
cables, and any other cables that are connected to the computer. Refer to “Left and right view”
and “Rear view” for help with locating the various connectors.
Step 4. Remove the rear cover. Refer to "Removing the rear cover".
34 Lenovo C240/245/255 All-In-One PC Hardware Maintenance Manual