It's my understanding that a dual rail PSU dedicates one 12V rail to the motherboard 20+4 connector, and the other rail is used for the various 3.5" and 5.25" devices onboard. Is this correct? I have 8 HDs, 2 DVD-RWs and I know that a 18A or 20A 12V rail won't cut it. I would be better off with a single rail PSU capable of 36A or 40A on the rail, with the mobo and all devices on that rail, right? Otherwise, I'd be underutilizing one rail and overutilizing the other.