Epson Progression U12 - Manual (Page 127)

The connector has two rows of holes designed to fit over the
pins in the drive socket. Notice the red wire running down
one side of the cable. This wire helps you orient the cable
connector to the drive socket. Align the connector with the
socket so the side of the cable with the the red wire faces the
drive’s power supply socket, as shown below.
red wire
Make sure the holes in the connector fit over all the pins in the
socket; then push in the connector.
8. If you removed the subassembly earlier, follow the steps in
Chapter 2 to replace it in your computer.
9. Replace the computer’s cover as described in Chapter 2; then
see “Post-installation Procedures” at the end of this chapter
to update your configuration.
4-24 Installing and Removing Drives