Dell Precision 340 - Manual (Page 19)

Hard-Drive Shroud and Hard-Drive Removal
5. Disconnect the power and hard-drive data cables from the drive.
Hard-Drive Cable Removal
6. Remove the drive bracket from inside the computer.
a. If a hard drive is already installed in the drive bracket, disconnect the power and hard-drive data cables from the drive.
b. Press in on the tabs on each side of the bracket, and slide it up and out.
7. If the replacement drive does not have the bracket rails attached, remove the rails from the old drive by removing the two screws that secure each rail
to the drive.
Drive Bracket Rail Removal and Replacement
1 hard-drive data cable
2 power cable
3 hard-drive connector (IDE PRI)