Epson Equity 286 PLUS - Manual (Page 126)

There is one 120pin power supply socket on the right side of
the main system board (toward the back) that holds both of
the power supply connectors, as shown below.
3. Position power supply connector P4 so the large tab on the
connector faces the right side of the computer. Beginning
with the six pins toward the back of the computer, carefully
line up the holes in the connector with the pins in the
socket. Then push the connector onto the pins.
5-36 Installing and Removing Options