The AT power supply connector pair was a notable exception, where you had to take care of lining them up correctly so that the ground wires go towards the middl

The AT power supply connector pair was a notable exception, where you had to take care of lining them up correctly so that the ground wires go towards the middle. And even though it is keyed, stronger people had no problems plugging in the 5¼" drive Molex connectors upside down.