Right, but say I have a 450 watt power supply with a motherboard with everything integrated. Video card, sound card, ethernet etc...

And they were all very low voltage...

Does that mean my PS is still using 450 watts or is it just using something more normal like 120 - 200 watts?

So I guess what I'm trying to ask is, is the PS still using 450 watts in order to just be there to support needed power or does it ramp up and use 450 only if a component needs it?