Epson 4000 - Manual (Page 83)

Caution
If you do not correctly align the holes with the pins, you
could severely damage your hard disk drive when you
push in the cable connector.
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