I got hold of a wattmeter today.

My system is made up of the following components:

Intel Core 2 Quad Q6600 (currently overclocked at a simple 3GHz to keep things cool)
4x1GB Corsair Dominator PC2-8500-C5
2x 500GB Samsung HD501LJ SATA2 7200rpm
1x EVGA Geforce 8800 Ultra Superclocked (for which you need a minimum of a 550W PSU)
EVGA Nforce 680i SLI Motherboard
Samsung 20x DVD-RW/CD-RW Drive

With these extra bits:

Dell 3007WFP-HC
Harman Kardon Soundsticks II
2x 120mm intake fans
1x 120mm exhaust fans
Stock processor cooler
3x 40mm memory cooler
1x 40mm chipset cooler

I am using a Tagan Turbojet 1100W PSU (yeah, 1.1kW baby!)
Guess how much I am using when I play the Crysis SP Demo in DX10 mode at 1280x800, in Very High detail mode?

I use less than 500W. This is taking the Dell 30 inch monitor and the 2.1 speakers in to account as well. And no it will not go any higher than this. The system actually peaks at about 405W when the monitor is turned off.

So all that stuff about "really, you could do with a 700W or an 800W PSU" is total and utter rubbish. But for you to have a 550W PSU as a minimum for a Geforce 8800 Ultra is a bit extreme.

One major thing to consider is what rails have what power, the Ultra sucks loads off the 12V rail, and that will need to be quite beefy to supply it. Basically buying bigger PSUs is just to be safe.

Out of interest, how were you measuring it?

It was a reading from a digital wattmeter.

Ah, where did you test from?

My house

I mean what did you measure across, where did you put the wattmeter etc?

In the socket in my wall.

LOL, OK. Got any smaller computers to test?

I could test my other computer, but my brother is using it right now.

Well it will be interesting to see the results.

How does the wattmeter work? As in how do you use it?

I will take a photo of it and show you

What would be interesting is seeing how much is used when I add the second graphics card. It looks like the 8800U sucks around 100W when under load. It would be interesting to see a power/performance ratio to work out the efficiency of the cards...

Hmm, that's quite interesting. I have a table here from a CPC labtest. It says their test system with a Ultra in sucked 312W of power un 3DMark06 load, for the entire PC. So it does seem 1000W PSUs may be a bit pointless.

It is also worth noting that the lowest power consumption, with the nVidia 7300GS, was 161W total, so the Ultra sucks atleast 151W of power, which is about half of the overall consumption, showing how power hungry graphics cards are.

My GTS 640MB came out at 269W. The biggest draw was the HD 2900XT at 355W.

My family PC spec:

AMD Athlon64 3700+ @ 2.3GHz
1GB Corsair XMS DDR400 RAM
ATI Radeon X850XT-PE
200GB SATA HDD, 7200rpm
1x 52x CD/RW
1x 16x DVD-ROM/CD-ROM
1x 120mm intake fan
1x 120mm exhaust fan

Standby: 6W
Sitting at Windows logon screen: 99W
Running F@H on the Windows desktop: 130W
Playing Crysis MP Beta: 180W

It has a 485W Enermax Noisetaker PSU. Overkill?

The monitor uses 21W constantly, 3W on standby.

Personally I would think a little bit of overkill is much better than underkill.

Of course, but I could have got away with a measly 300W power supply here!

The computers at work use a maximum of 100W under load. I haven't checked the power supply watt rating for them though.

Yes, but that is if it supplies it perfectly correctly for you. PSUs don't function too well at max capacity either. A 500W one would probably have been fine, though with another Ultra you'd want 700W atleast.

You're exactly right. 700W would be perfectly acceptable with enough headroom for my system to work reliably (as long as it has 4 PCI-E connectors).

Indeed, but I still say a lot of leaway is better! It's not like a more powerful PSU uses more power when not needed, after all.

But they do come with fewer cables and in modular forms... get my drift?

Well yeah, but so do more powerful ones! If you get the right one that is. xP

But it'd be money wasted I have wasted lots of money!

Hmm, true, but not that much compared to some of your other spendings... lol

Well, at least I can say I am 100% satisfied with my other products. I feel that I got what I paid for.

You got what you paid for with your PSU too. Just you didn't need it all.

Seems that's not so true now, considering it just blew up.