Which power do I need ?

I plan to build the following config:

* CPU: AMD Phenom II X4 955 BE 3.2GHz
* M/B: Gigabyte MA-790XT-UD4P
* RAM: OCZ Extreme Edition 4GB (2x2GB) DDR3-1600
* GFX: XFX or eVGA GeForce GTX 260 or GTX 275
* HDD: WD Caviar 640GB 7200rpm SATA
* DVD: Pioneer DVD-RW 20x SATA
* Case: not sure yet (thinking at LIAN LI PC-65B...). I guess that's not so important as for the PSU
* PSU: that's precisely my question !

Could you indicate the minimum power I need for a PSU and recommend a few brands? Is there any other of the PSU specs I need to take into account to get the correct/suitable PSU for my config?

This system will be powered on 24/24.

A single GTX 260 video card will draw about 200 watts and 16 amps at full load. The GTX 275 has similar requirements. The power consumption may be a little lower. Different references show slightly different figures.

If you do not overclock the cpu, then the rest of your system will probably use another 200 watts. Your minimum requirement would be a high quality 500 watt power supply.

If you overclock the cpu then, then the rest of your system will probably use about 300 watts. Your minimum requirement would be a high quality 600 watt power supply.

The Antec Earthwatts EA500 would be a good choice for a 500 watt power supply. It can handle just about any single video card made:

http://www.newegg.com/Product/Prod [...] 6817371007

Here's a link to a technical review over at jonnyguru.com:

http://www.jonnyguru.com/modules.p [...] ry&reid=35

If your system is powered up 24/7 then you should find out what your system draws at idle or what your system draws the majority of the time (I found an approximation by using another power supply temporarily, and using a power meter and guestimating on efficiency). Since most power supplies tend to be most efficient close to 50% of their rated power you should find one that is most efficient when you're idle yet can handle the power requirements when you are gaming or doing other power intensive tasks. You should at least look for a power supply that is 80+ efficiency rated if not higher. Some well known brands to look at are PC & Power Cooling, Corsair, Seasonic. Have fun on your search.

Many thanks for your answers!

I forgot to indicate that I might try to overclock the graphics card. Does this make any change as for the minimum power required for the PSU?

Well now totally off the topic...
I just noticed that you have just planned to build the rig...
Looking at the graphics card options,
Are you nvidia specific? If yes, then its fine...
But if you are also OK with ATI, then I guess instead of the GTX 275, you should get the HD 4890...
Reason :
1. You can later crossfire 2 HD 4890s on that mobo and not SLI the GTX 275.
2. Even the HD 4890s are very good overclockers.

Another best alternative :
If you are OK with crossfire, then drop all the graphic card options and get 2 4770s in crossfire...They perform as good or better than the 4890s/ GTX 275 and cost $100 each...

But finally the choice is yours...

well, even if you only have x16 x8 crossfire, the x8 is plenty for single gpu cards, so if you do go with the 4890, then it wouldnt be a problem

Like I said 550w would be your sweet spot.

If your going to Crossfire two 4890's down the road, then go for that 650w Corsair.

I will very likely go with the following PSU, which was recommended to me by the local vendors for its good quality/price value, and costs $48: Tsunami Technologies Power'On 685W

Has anyone heard of this brand? ANy comments?

Looks like crap to me. Buying a PSU based on price is a bad idea; it's the most important component in your system.

Yes, it's in the specs. But what does it mean exactly?

It means it is junk. All good current PSUs achieve well over 80% efficiency, with some hitting 90%.

None of those are very good, where in the world are you?

Corsair, Pcpower and cooling, BFG, OCZ, FSP (Fortron Source) Antec, all are good brands, make sure you get one thats a minimum 80% efficient. Surely one of those brands is available.

I am in Thailand. I think that I have seen some Corsair PSUs in some local shops, but the wattage was around 800W, much more than what I need. I'll take another look around and see if I can find a Corsair or another good brand PSU of appropriate power for me (~550W).