It is not only based on watts! If it is a modern unit with big portion of its power on the +12volt rail (around 30amps) it should work fine. If not then a PSU upgrade would be needed. Can you post the full model number of the PSU?
You will have to and when you do look to see how many amps are on the 12 volt rail. I can not find one spec for your unit which usually means it is compete crap. Not to mention I looked at a few PSU blacklist and yours is on it.
I personally would not suggest powering a HD5850 with that unit it could blow up and take the rest of the PC with it. I would get a better power supply before installing that card unless you don't mind replacing your whole system when it blows.
Guys, you really have to google about a power supply ?
27 euros power supply are good for a onboard graphic and that's it.
a 200 euros with a 27 euros power supply doesn't work at all.
Cheap power supply are = small ticking bombs.
It might work, yeah, but you might fry everything in your system.
My friend fryed a dual core + 4 gb ram + a 4870 + 2 hard drives with a *** power supply.
I told him to change it and he told me with a smile, RELAX BUDDY IT WORKS FINE.
Anyways, throw your current power supply at garbage and buy a Seasonic S12ii 520 watts and you can sleep okay
Seasonic S12ii 520 watts might be expensive but it worth it.
Else I would go for a Cooler Master eXtreme Power 600 watts, never had any problem with them even if they aren't the best on the market, for the price you pay you get a decent quality and it will be 1000000 times better than your bomb.
Personally, I see no value to buying < 650 watts as the cost savings for anything decent is insignificant. XFX has been very aggressive of late on their pricing and they remain the best buy right now for PSU's. The Black Editions garner 10.0 performance ratings from jonnyguru.com and the Core Editions are getting 9.5's.
You are wrong, buying a smaller ake thigher power supply is better for efficiency.
buying a 1000 watts power supply for a 400 total watts rig is complete stupidness.
the best is 0.5-0.75
In your case I wouldn't take higher than 600 watts.
The best efficiency for a power supply is about 50-75% of usage.
And please do not rely on antec's calculator, your rig will max draw 400 watts.
A good 500 watts will do the job better than an higher wattage power supply.