Poweruse by a 700W PSU?

It will only use whatever the system needs from it. My system pulls 150 at idel up to 350 while playing oblivion at 1600x1200 with everything maxed out from a 500watt ps with an athlon 64 3700+, Radeon 1800xt, 2 HD's, 2 optical drives, and an SB Audigy2.

No, never. Thats merely the peak output. Almost could be called the 'worst case senario' output. When you processor and videocard etc etc are doing 'more' they consume more watts. Thats why when you are only checking emails and browsing the web, your cpu's tempature is relatively low.

Kill-a-Watt is sort of a monitor for your plugged in devices usuage. That one is about 39.99 USD and ive seen similar models for half that. If you ever see that approach even 400 watts, id be "shocked".

Power supplies typically only consume 15-30% of the total system power during the conversion process, leaving 70-85% of the power for the system. The amount the consume varies therefore with the load placed upon them.

Power supplies are also typically most efficient at around 70% load, give or take 10% depending on the design. That means going "overkill" on power supply size does have the chance to decrease efficiency slightly. But we're not talking about dollars a day difference, more like spare change.

Thanks alot guys that is good news. Electricity is sooo expensive in Denmak. I was afraid that the power not used by the computer was turned into heat in the PSU so that the PSU would become the hottest when the computer was iddle.

No, but the typical high-end gaming system uses around 200-250W under normal use and around 350W during games, and the typical power supply will operate at lower efficiency using only 50% of its available capcity.

Generally speaking I prefer to use efficient power supplies with only 100-150W excess capacity, so that I'll be in the "sweet spot" ~70% load while gaming.

Hey Zar,
That was a great question....
And thanks as well for the answers to his question because I always wondered the same thing. My wife always nags me about turning off my rig when I 'm not using it.......I have a 600 W SeaSonic S12....so naturally I thought that when it was running......it consumed .....well....600 Watts 8O

RIG specs
Antec P180 PerformanceSeries Mid-Tower Case
SeaSonic S12 600 watt power supply
Asus A8N32 SLI mobo AMD N-Force 4 SLIX16 (bios 1103 V02.58)
RealTek 97 onboard digital 5.1 Surround
AMD Athlon 64 X2 4800+ Toledo Core, 2 X 1mb L2 cache (AMD driver 1.3.1.0 w/MS hotfix)
2 gigs of Corsair TwinX3500LL Pro @ 437Mhz 2-3-2-6-1T
2- BFG Tech 7900 GT OC 256mb in SLI (nvidia driver 91.31)
Western Digital RAPTOR 74.3 gig 10-K rpm HDD for XP & Apps
Maxtor SATA II 250 G HDD for gaming, movies, MP3's
Maxtor SATA II 250 G HDD for document backup (unplugged)
Sony CD rom 52X
Plextor 708-A DVD/CD rom
Logitech Z-5500 digital 5.1 THX Surround 500watts

nah the rig will only consume as much power as it needs. Also turning off ur pC once in a while is a good thing. I opted for an opteron so i could leave it running for weeks on end but the most i've ran my system was 4 days straight.

I run all of mine 24/7/365 except when I need to upgarde or reboot for os related stuff. 2 Athlon 64's, 2 Athlon XP's, and a bunch of older intel stuff, never have a prob. And since three of my servers cost all of $16 a year to run, I'm not too worried about the bill  

edit: Keeping the machine on puts less expansion stress on parts since they run at a more stable temp then from on to off to on again. In my mind it's less stress than 24/7 operation, but I don't think anyone has come up with scientific fact about that yet. Course besides my servers, my other machines are always downloading torrents and the such so I can't shut them off.