Dell Precision 390 - Manual (Page 73)

empty bay (see About the Metal Shields Present in Some Drive Configurations ). Then, install a drive-panel insert (see Replacing a Drive-Panel Insert).
Installing an Optional Third Hard Drive (Desktop Computer)
1. If you are installing a new drive, unpack the drive and prepare it for installation.
Check the documentation for the drive to verify that it is configured for your computer.
2. If you are installing a new drive, remove the drive panel (see Drive Panel ) and the drive-panel insert (see Drive-Panel Inserts ) from the lower 5.25-inch
drive bay.
If you already have a drive installed in the lower 5.25-inch drive bay, remove the optical or hard drive.
3. Place the hard drive in the hard-drive bracket and press the drive down until it snaps securely into place.
4. Slide the hard drive in the hard-drive bracket into the hard-drive holder.
5. Slide the hard-drive holder into the lower 5.25-inch drive bay until it is securely seated.
CAUTION: For configurations with three SAS hard drives, you must install an additional fan. See Installing an Additional Fan .
1 hard drive 2 hard-drive bracket
1 hard-drive holder 2 hard drive in hard-drive bracket