Yellow = +12V
Red = +5V
Orange = +3.5V
On the ATX connector block any one of the above may have another thinner wire next/joined to them that is a voltage sensing wire. The Orange wire sometimes has a brown 'sense' wire next to it...
Black = Common~Earth (for +3.5V, +5V and +12V)
Grey = Power OK
White = -5V
Blue = -12V
Green = Power Supply ON
Purple = +5V Stand By (+5VSB)
The main ones are Red= +5V, Yellow= +12V, Orange = +3.5V/3.3V and Black= Common~Earth
OK?...