The following lines were added (+) and removed (-):
The original PC starting in 1981 used two cables (Molex 90331) to connect the power supply to the motherboard. They connected side by side into the motherboard, and they could easily be reversed accidentally, or inverted which will result in damage to the motherboard. When connecting them to the motherboard it was important to observe the "black to black" rule.{||- align="center"! colspan="3" bgcolor="#c0c0c0" | Pinout|- align="center"! bgcolor="#c0c0c0" | Pin number! bgcolor="#c0c0c0" | Wire color! bgcolor="#c0c0c0" | Description|-| align="center" | 1| align="center" | orange| align="center" | power good|-| align="center" | 2| align="center" | red| align="center" | +5 volts or connector key|-| align="center" | 3| align="center" | yellow| align="center" | +12 volts|-| align="center" | 4| align="center" | blue| align="center" | -12 volts|-| align="center" | 5| align="center" | black| align="center" | ground|-| align="center" | 6| align="center" | black| align="center" | ground|-| align="center" | 1| align="center" | black| align="center" | ground|-| align="center" | 2| align="center" | black| align="center" | ground|-| align="center" | 3| align="center" | white| align="center" | -5 volts|-| align="center" | 4| align="center" | red| align="center" | +5 volts|-| align="center" | 5| align="center" | red| align="center" | +5 volts|-| align="center" | 6| align="center" | red| align="center" | +5 volts|}On an AT system the power supply delivered a majority of power at 5 volts since most of the motherboard ran at that voltage. One rail was 5v and the other 12v.