Can anyone help me with calculating the peak wattage for the following system. I've tried various online calculators, such as the one at www.extreme.outervision.com/psucalculatorlite.jsp, but they give absurd wattages - e.g. 850W or more.

1 x Core 2 Quad Q6600 @ 3.2GHz
1 x GeForce 8800 GTX @ stock
1 x High end motherboard
4 x 1Gb DDR2 RAM
1 x SB X-Fi sound card
2 x DVD+RW units
2 x 7200rpm harddrives
4 x 800rpm 120mm fans (two for CPU / GPU cooling, the rest for the case)
5 x USB units, e.g. webcam, wireless mouse etc

I'll probably build this in a P182 case, and I'd like to keep my Corsair HX520 PSU if possible.

Many thanks

~410W.

Actually, I think that calculator just recommends a PSU (in this case 850W), it doesn't seem to tell you how much your rig will draw. (Link didn't work, but I've used the calc before).

Simple Estimate, about 300-350W at absolute maximum load..and likely 180w or less at idle. If you're using a Corsair HX520, it is more than enough. You could probably get by on a "420" if it existed imho. I think the days of overinflated psu numbers must die!

Simple and to the point I guess. Be nice to know how you derived at this figure though.



Sorry about that, link is fixed.



I agree that PSU requirements are overinflated, but one could of course argue that is also the case with CPU / GPU speeds, digital camera megapixels and so on. Guess it's a matter of knowing what is enough for me, which isn't always the biggest. I'll wait for the next generation of games in Q4 before deciding if I need to upgrade to Quad etc, but it needs to run smoothly on a 24" screen. Good to know my current PSU will suffice though!

CPU: 150W (105W + 33% OC + wiggle room)
GFX: 150W (132W [link] + wiggle room)
M/B: 20W
RAM: 4W
PCI: 3W
DVD: 40W (burning)
HDD: 40W (spin-up)
FAN: 4W
USB: 2W

= 413W

you can subtract about 60W during normal max use because DVD drives unlikely to be maxed out at same time as GPU+CPU, and each HDD only takes ~10W after spin-up.

Excellent! Many thanks for your help.