Originally Posted by Disillusion
Overclocking, by itself, does NOT add voltage. If you add voltage through a BIOS flash, that's different. Overclocking only raises clock speeds.
The reason the XPS comes with a bigger power supply is because their video cards use more power.
Umm, you don't need to increase the voltage to draw more power. Overclocking, even when it doesn't increase voltage, ALWAYS increases power usage.
When you overclock components, they get hotter. And where do you think that heat comes from? You don't get more heat unless you're drawing more power. So of course, you're going to draw a lot more than 20W for the 7900gs if you're overclocking it, even without increasing the voltage.
Except, we ARE increasing the voltage, from 1.00v up to 1.24v. Since we're overclocking AND volt modding, the increase in power drain is quite significant. And if you run the i9400 at 600/800 (1.24v) and use up 100% of both cores of a 2.16GHz Core 2 Duo CPU, and the power supply is in a warm room (perhaps on carpet), it WILL fail (temporarily).
Also, don't forget, power supplies provide LESS power the hotter they get. That's one of the problems with cheap noname ATX power supplies. They say 350w, sure, but that's 350w at perhaps 25 degrees. Once they get into operation and hit 40 or 45 degrees, they provide significantly less. Good companies like Antec specify capacity at operating temperature, not room temperature. The i9400's power supply gets pretty damned hot when you're running a game at 600/800.