8350 to answer your post OP.....it will run fine with a 280. You see, its very simple. In fact I feel foolish explaining this to you as I know you would have found it eventually....When the quotient of pi exceeds the variables put forth with...yeah...i said forth with you get the quantum perplexity of 2.36, given that the ambient is 4, you get 7.453. If you follow the logical path that this provides, you will end up at the inevitable conclusion that the R9 280, being a 7950 in new skin, can cope with the 8350, which is clocked at 4.0GHz.. Thank you and have a good day B) :P
As you can see, I am a AMD user and at this point, for what I do, am very content with my rig. When Zen rolls out, hopefully it will put AMD back in the running, as competition is good for business. Good luck with whatever you choose and happy gaming