Lenovo 4155 Personal Computer User Manual


 
Notes:
a. Do not remove the plastic cover until you are ready to install the heat sink and fan assembly on the
microprocessor. Do not touch the grease on the heat sink and fan assembly. Do not put the heat
sink and fan assembly anywhere except on the microprocessor after the plastic cover has been
removed and the grease exposed.
b. Some heat sink part numbers will have orientation labels showing "Front of System." Heat Sinks that
do not have orientation labels should be oriented so the fan cable is toward the board connector
labeled "CPU Fan."
7. Place the new heat sink into position.
Important: Do not touch the thermal grease while handling the heat sink.
8. Align the four screws on the heat sink with the four mounting studs in the chassis.
9. Follow this sequence to install the screws, noting that fully tight is 5 in-lbs +/- 0.5 in-lbs:
a. Partially tighten screw 1 , then fully tighten screw 2 , and fully tighten screw 1 .
b. Partially tighten screw 3 , then fully tighten screw 4 , and fully tighten screw 3 .
10. Reconnect the heat sink fan cable. See “Locating parts on the system board ” on page 113.
11. Go to “Completing the FRU replacement” on page 108.
Replacing the microprocessor
CAUTION:
The heat sink and microprocessor might be very hot. Turn off the computer and wait
three to ve minutes to let the computer cool before opening the computer cover.
Attention
Do not open your computer or attempt any repair before reading and understanding the “Important safety information”
in the ThinkStation Safety and Warranty Guide that came with your computer. To obtain a copy of the ThinkStation
Safety and Warranty Guide, go to:
http://www.lenovo.com/support.
This section provides instructions on how to replace the microprocessor.
To replace the microprocessor:
1. Open the computer cover. See “Removing the cover” on page 78.
2. Place the computer on its side to help make the system board more accessible.
3. Remove the heat sink from the system board. See “Replacing the heat sink” on page 90.
4. To remove the microprocessor 3 from the system board, lift the small handle 1 and open the retainer 2 .
122 ThinkStation Hardware Maintenance Manual