Dell OptiPlex 755 - Manual (Page 159)

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