Your Raidmax PSU is junk. I was surprised that someone is actually running a HD6850 on it; I'm sure a GTX560Ti or GTX570 would overload it and kill it. Cheap PSUs like to take other parts with them into the fiery abyss, so you'll need to replace it first. A quality modern PSU has full range active PFC (no little voltage switch) and some level of 80+ certification for efficiency. Seasonic, Antec, Corsair, XFX, and Enermax/LEPA are among the better brands. A good 500W PSU like an Antec Earthwatts can run almost any single GPU.
Considering you're suffering with Intel's Highly Deficient graphics now, you could drop in this GT440 for a few months: http://www.newegg.com/Product/Product.aspx?Item=N82E16814130612
then step up when you upgrade your PSU.
Edit: Saw your PSU has a "630W" label on it, not "530W." It's still a Chokemax, and still junk. I would not trust it to run a powerful GPU.