Originally Posted by Misfire
OK, now I'm no EE, but I have had electrical class's, what make's heat? currant flow, (amps) if cut in half, should drop temp's with same powr usage!
No... You are doubling voltage but halfing the current.
10A * 120v = 1200w
5A * 240v = 1200w
In your case, you are improving the PSU efficency by a few percentage points. This will reduce the heat dump by the PSU.
i.e. If your system needed 500W and the PSU was running at 85% efficency, the PSU would be generating ~88w of waste heat. Moving the system to 240v would improve efficency by say 3%. So your 500w system is on a 88% efficency would reduce waste heat by 20w.