Dell Precision 690 - Manual (Page 72)

7. If an empty 3.5-inch drive carrier is installed in the drive bay, slide the Media Card Reader into the drive carrier until it clicks into place.
Otherwise:
a. Slide the Media Card Reader into the 3.5-inch drive carrier until it clicks into place.
b. Then, while pressing down the release lever on the side of the drive carrier, slide the drive carrier into the drive bay until it clicks into place.
8. Attach the interface cable to the Media Card Reader.
9. Connect the other end of the interface cable to the system board connector labeled "USB." To locate the system board connector, see System Board
Components .
1 Media Card Reader
2 screws (4)
1 Media Card Reader
2 floppy drive/ Media Card Reader carrier