Dell OptiPlex 100-Mbps Service Manual page 55

retaining tab (2)
Figure 4-10. 5.25-Inch Drive Removal
To remove a 5.25-inch drive from the middle or lower drive bay, follow these
steps:
1. Disconnect the DC power cable and the interface cable from the back of
the drive.
2. Press out on the two retaining tabs on the sides of the drive bay, slide
the drive forward, and remove it from the drive bay.
Removing and Replacing Parts 4-11