Dell Precision 3640 Tower Service Manual page 44

Steps
1. Insert the cables through the IO panel slot on the chassis.
2. Insert the IO panel tabs into the slots on the computer chassis and replace the single (#6-32x1/4') screw to secure the IO
panel to the computer.
3. Route the cables through the routing channel and connect the following cables to their respective connectors on the system
board:
a. IO USB cable
b. Type-C cable
c. SD card cable
d. System board power connector cable
Next steps
1. Install the optical drive.
2. Install the bezel.
3. Close the psu hinge.
4. Install the cover.
5. Follow the procedure in
44 Disassembly and reassembly
after working inside your computer.