Dell Vostro 470 (Mid 2012) - Manual (Page 22)

Installing The Rear System Fan
1. Place the fan towards the center of the computer into the chassis.
2. While holding the chassis fan in place, replace the screws that secure the fan to the chassis.
3. Reconnect the fan cable to the system board.
4. Install the cover.
5. Follow the procedures in After Working Inside Your Computer.
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