Optiplex 755 unidentified unplugged cable

While taking first steps to replace the HD, i.e. Unplugging and removing DVD drive, may have accidentally unplugged something else--it is a small white plug, approx 5/8" long X 1/2" wide--plug end has 4 very small female apertures, 4 very small gauge wires attached, Rd Bl Bl Yllw--on one side is stamped P4--a single ridge on the plug would prevent it from being plugged in backwards--will try to attach a picture Tax, RW