Agree with unksol. They make bad PSUs on the low end. I recently had a 400w psu with 2 x +12v rails and each rail had 16A. But there were so many problems with powering up my gtx 550 ti which require only 24A in +12v rail. As unksol they can't deliver what they are rated or lie in the rating.
Honestly, I can't find a review of that PSU, but i have been up pretty much all weekend... 48 hours at least... and i post on toms to avoid work boredom so my google skills are about worn out. Look around for somone who tears them down for a good reveiw. Jonny guru. Hardwaresecrets.... there are other but again my brain is about shot.
You are better off with the 7850 for a few reasons. One of which is that it will cost you less to use it (electricity costs money) Since you are on a budget look at things beyond the initial price tag.
The 7850 will leave more headroom for the future with 2g vram. Using 1 card over a xfire set up is more user friendly.
Without doing any of the research myself (I encourage you to do it) your current psu should be enough if you are not overclocking.
Yh i researched the PSU and it would theoretically handle it, however i dont really wanna risk starving the cards of power and it would be a risk so i think i'll go with the 7850. As you say the savings on electricity and the headroom make the 7850 the right choice. I think i kinda new already, just wanted some reassurance . Thanks all for the help.
I agree with all above stated. The 7850 would be the most logical choice since there is no definitive answer as to whether or not your PSU will cut the mustard, and the last thing you want is PSU problems to cause further financial investment.
LOL, take into account that there are bad and good psu's this is why they recommend 650watts.
a decent 500 watt can push 6850 CF rather easily.
Do a psu calculation here: http://extreme.outervision.com/PSUEngine
Came to 457 watts with an overclocked i5 2500k at 4.5ghz 1.32v with 4 120mm fans 1 7200rpm hdd and a dvd drive.
LOL, and where is that "bad and good" thing written? there is so many psu calculators.. from newegg to thermaltake.