Dell OptiPlex 7020 (Mid 2014) - Manual (Page 21)

3. Disconnect the system-fan cable from the system board.
4. Pry and remove the system fan away from the grommets securing it to the front of the computer.
Then, press the grommets inward along the slots and pass through the chassis.
Installing the System Fan
1. Place the system-fan in the chassis.
2. Pass the grommets through the chassis and slide outward along the groove to secure it in place.
3. Connect the system-fan cable to the system board.
4. Install:
a. front bezel
b. drive cage
c. optical drive
d. cover
5. Follow the procedures in After Working Inside Your Computer.
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