There's no cooler master in my links. Stay away from cooler master.
why stay away from coolmaster? it has some decent reviews.
Did you find a good independent review of the CM 650GX? Those customer reviews ('it works good for me') don't always give you a good indication just how good a PSU it really is.
Customer reviews are of extremely limited value. Look for a competent technical review (e.g. jonnyguru, hardwaresecrets) that includes load testing and waveform analysis under realistic operating conditions. Some Coolermaster PSUs are garbage, a few of the newer ones are good. All Antec (except <500W Basiq), all Corsair, and all Seasonic are good. Unless you're planning to Crossfire, then as mosox said 650W is enough.
psu is the only part which i dont have deep understanding about, i dont get whats the difference between quad 12v rails compared to single powerfull rail. i DONT KNOW which 1 is better and provides higher power for sli or single card.
can any 1 explain should i get a quad rail psu or single and if so why?. and secondly which 1 will provide more then enough power for my setup. 1 last thing... whats the difference between the two i mentioned above^ ?
A multi-rail PSU can be safer. There's marketing in it too, of course, but read the vendor voice thingy from Antec on Tom's main page. That explains it pretty well.
I could not find any review of the OCZ GameXStream 850Watts which is a little unusual. Given the the price of the Corsair 850TX is only £24 more and it comes with a 5yr (vs 3yr for OCZ) warranty I think it might be a smart move going with Corsair. Corsair TX850 Power Supply review @ JonnyGuru