Dell OptiPlex 990 (Early 2011) - Manual (Page 16)

Installing The Front Bezel
1. Insert the hooks along the bottom edge of the front bezel into the slots on the
chassis front.
2. Rotate the bezel towards the computer to engage the four front-bezel retention clips
until they click into place.
3. Install the cover .
4. Follow the procedures in After Working Inside Your Computer .
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