Dell OptiPlex 990 (Early 2011) - Manual (Page 55)

3. Close the expansion-card latch.
4. Connect the cables to the system board.
5. Install the heat sink and processor .
6. Install the expansion card .
7. Install the hard drive .
8. Install the front bezel .
9. Install the cover .
10. Follow the procedures in After Working Inside Your Computer .
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