Dell OptiPlex XE2 (Mid 2013) - Manual (Page 28)

Installing the Heat Sink
1. Place the heat sink assembly into the chassis.
2. Tighten the captive screws to secure the heat-sink assembly to the system board.
3. Connect the fan cable to the system board.
4. Place the heat sink cover.
5. Install the:
a) cover
6. Follow the procedures in After Working Inside Your Computer .
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