Dell OptiPlex 755 User Manual page 159

1 release tabs (2)
2 hard drive
3 hard drive bracket
4. Connect the hard drive fan cable to the system board.
5. Connect the power and data cables to the drive.
1 power cable
2 SATA data cable
6. Check all connectors to ensure that they are properly cabled and firmly seated.
7. Gently position the drive until it clicks into place.
1 release tabs (2)
2 hard drive
8. Replace the computer cover (see
9. If the drive you just installed is the primary drive, insert bootable media into your boot drive.
Replacing the Computer Cover).