Epson EL 486UC - Manual (Page 85)

5. Locate one of the power supply cables that lead from the
power supply. (They have multi-colored wires and a plastic
connector on the end .)
6. Position the power supply cable connector so that its notched
corners line up with the notched corners of the power
supply connector on the hard disk drive.
7. Make sure the holes fit over all the pins and then push in the
connector.
Caution
If you do not align the cable connector correctly, you could
severely damage your hard disk drive when you push it in.
Installing and Removing Drives 5- 7