Dell OptiPlex 9020 All In One (Mid 2013) - Manual (Page 31)

4. Remove the screws that secure the speakers to the chassis. Lift the speakers from the computer.
Installing the Speakers
1. Place and align the speakers on the chassis. Tighten the screws that secure the speaker to the chassis.
2. Thread the cables on the notches. Connect the speaker cables to the system board.
3. Install:
a) system-board shield
b) VESA mount bracket
c) back cover
d) VESA stand
4. Follow the procedures in After Working Inside Your Computer .
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