Dell Precision 3640 Tower Service Manual page 67

Figure 10. VR heatsink assembly for systems shipped with 65 W or 80 W CPU
Figure 11. VR heatsink assembly for systems shipped with 125 W CPU
Steps
1. Align and replace the VR heatsink on the system board.
2. Tighten the captive screws that secure the VR heatsink to the system board.
Disassembly and reassembly 67