Dell OptiPlex Gxi - Manual (Page 106)

1. Disconnect the DC power cable and the interface cable from the back of the drive.
2. Press in the two retaining tabs (one on each side of the drive), and slide the drive assembly forward to remove it.
5.25-Inch Drive Removal
Remove the four screws attaching the 5.25-inch drive to the drive bracket, and lift the drive out of the bracket.
When you replace the 5.25-inch drive, align the front of the drive flush with the tabs at the front of the drive bracket. Insert the four screws, and tighten them in the
order stamped on the bottom of the bracket.
Hard-Disk Drive Bracket Removal