PSU power consumption question

[nick111]

I'm building my computer with much thought on power consumption. I will not be overclocking and have the E6750 CPU, P5k-E mobo, 2 gigs of ram,1 DVD writer, 2 hard drives. I have an Antec NeoHe 500 watt available to use and has plenty of amperage. Now I know I can get away with a smaller psu. Will the 500 watt be too wastefull? How much more electricity will the 500 watt consume versus a smaller psu, say a 400 watt? Or does it not matter since the only consumption is what the components are drawing? Thanks

 

[cfvh600]

The consumption will be limited to what the components are drawing.

 

[jsc]

Plus PSU losses.

All other factors being equal, a 500 watt PSU operating at 80% load will be more efficient than a 400 watt PSU operating at 100% load. Losses will show up as heat, so the more efficient PSU will run cooler.