whats power psu do i need for such system:
AMD ATHLON 64 X2 5400+ AM2 (65W) BOX
GIGABYTE MA770-DS3 AM2+ 790FX+SB600
2X A-DATA 1GB DDRII 800 128Mx8
GIGABYTE GV-R485-512H-B/ HD 4850/
2xHDD
DVD drive

any specific model?

For a HD 4850 Sapphire recommends a 450W PSU: http://www.sapphiretech.com/us/pro [...] p?gpid=244 Look under System Requirements

Antec Earthwatts 430 / Corsair 450VX / OCZ StealthXstream 500 / Antec Earthwatts 500 Any of those would give you plenty of power and the prices are reasonable for quality PSUs.

A cheap 680W PSU may blow when you pull 400W-450W out of it. A quality PSU (e.g. one actually good for its rated capacity) of 500W should be sufficient for that system.

I was looking through some motherboards earlier and I came across this review of a Gigabyte motherboard. Not only did the person try to save a few bucks buy buying a crappy PSU he actually blamed it on the motherboard.

"I bought a Rosewill power supply, first one had a bad capacitor, and ended up frying the first gigabyte mobo with it when I booted it up. RMA'd both, and had it happen again when the new stuff came in. The board seemed highly sensitive to power fluctuations from my second Rosewill RV600V2 power supply. I guess it could be a great board if my two different PS from Rosewill hadn't blown the thing up. The second PS ran, but pushed out some real bad inconsistent power. I can only return it for yet another replacement with newegg, which I'm not going to do. So i'm out the $230 the mobo and PS cost me, plus another $40 in shipping or so."

There is no more important part of a computer than a quality PSU. Every part relies on solid, stable power and a cheap PSU has the ability to take out a whole system. All the models mentioned earlier are good products but I just wanted to mention this in case you were thinking of going cheap.

Look for a high quality 500/550W PSU. You really shouldn't need anything more than that unless you end up CF'ing your video card. WR2 recommended the Antec Earthwatts and I agree with the recommendation. Depending on how much you want to spend, there are plenty of other high quality 80+ PSUs out there as well. Just watch out for lightweight, low quality PSUs because you're more than likely to have problems down the road.

OK guys, thanks for your help
BTW what do you guys think about this model ?:
CHIEFTEC PSU ATX/EPS 550W PFC 12CM 27DB

Hard to say without a review to judge it with. It's probably a low end PSU but not necessarily a bad PSU.
Can you find any links on the Chieftec site? or a review of that PSU?

Ideally you'd want to have a PSU reivew like this one: Antec Earthwatts 500 http://www.jonnyguru.com/modules.p [...] ry&reid=35

And not a review like one of these: http://www.jonnyguru.com/modules.p [...] ry&reid=71

Chieftec is garbage.

Use this as a guide, get something no lower than tier 3

1+

@ ausch30; What do you base your garbage rating on? Chieftec isn't in the tiered listing.
Some of their PSUs are made by CWT or Delta and are pretty well regarded in the JonnyGuru forums.

edit;
Looks like BXCracer may be talking about the Chieftec Smart Power series
JonnyGuru forums thinks they're made by Delta and that it's probably a "good" PSU.
http://www.jonnyguru.com/forums/sh [...] t=chieftec

I misspoke, I don't think they are garbage but there are much better units out there

Agreed; they're only "good" units not "better" like a Seasonic built Antec EA 500 & Corsair 450VX or the CWT built Corsair 550VX.
The Chieftec Turbo series built by CWT would be a decent option in areas where people dont have access to Corsair models.

Yes i was talking about this model GPS-550AB-A. forgot to post it earlyier, sorry.