Dell OptiPlex GX520 User Manual page 171

1 drive
2 release tabs (2)
3 hard drive bracket
4. Connect the power and hard-drive cables to the drive.
1 power cable
2 serial ATA data cable
5. Check all connectors to be certain that they are properly cabled and firmly seated.
6. Gently position the drive until it clicks into place.
1 release tabs (2)
2 hard drive
7. Check all connectors to be certain that they are properly cabled and firmly seated.
8. Replace the computer cover.