Quote Originally Posted by TRICHEESE View Post
i didnt think that there would be a problem with that as the higher voltage flows to the lower one, and it will always flow like that unless there is a diode or something else to restrict the current to flowing from 5v to any other lower voltage, it doesn't matter whether the lower voltage is 0v or any other number below 12v, the current will still flow from +ve to -ve.
well i heard it can introduce noise to the 5V rail.

Since the 5V and 12V are independant off each other, when you mix to the 2 to get 7V, i heard thats not great on a psu under load conditions.