Epson Endeavor WG - Manual (Page 111)

2. Locate the hard disk drive ribbon cable that came with the
computer. It is a flat cable with three connectors: one on
each end and one in the middle, as shown below.
connector
connector
3. Select the connector on the end of the longest part of the cable.
Notice the small tab in the middle of the cable connector;
align this tab with the notch in the system board connector,
as shown below. (The option card connector board and
diskette drive ribbon cable are removed from the
illustration for clarity.)
3-34 Installing and Removing Drives