Dell OptiPlex 390 (Mid 2011) - Manual (Page 56)

Installing the System Board
1. Align the system board to the port connectors on the rear of the chassis
and place the system board in the chassis.
2. Tighten the screws securing the system board to the chassis.
3. Connect the cables to the system board.
4. Install the
heatsink and processor .
5. Install the expansion card .
6. Install the front bezel .
7. Install the cover .
8. Follow the procedures in After Working Inside Your Computer .
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