Dell OptiPlex GX260 Service Manual page 30

1 bracket caught outside of slot
2 bracket within slot
3 fully seated card
4 not fully seated card
7. Before you lower the retention arm, ensure that:
The tops of all cards and filler brackets are flush with the alignment bar.
The notch in the top of the card or filler bracket fits around the alignment guide.
Press the arm into place, securing the card(s) in the computer.
Closing the Retention Arm