Dell OptiPlex GX260 Series System User's Manual page 117

1 retention arm
2 filler bracket
3 adapter bracket
8. Remove the filler bracket.
9. Slide the adapter bracket down over the card slot opening, and lower the retention arm, securing the adapter bracket.
10. Route the serial card cable under the card cage, and attach the cable to the connector on the system board (labeled
SER2).
Replacing the Card Cage and Connecting the Cable