I wouldn't pair a 280x with a Clarkdale i5, that will bottleneck. Even the Lynnfield i5s (Core i5 7xx) which are actual quad cores can be a bottleneck to a 280x on some titles without an overclock.
I wouldn't bother with anything higher than a lower midrange GPU unless you plan on transplanting it to a new build sometime in the foreseeable future.
You should be fine.. you may see a small bottlene k in cpu intensive games but cpu will not bottleck the gpu much or not at all... your cpu can handle a 750ti whick is what the 950 is replacing.
I wouldn't pair a 280x with a Clarkdale i5, that will bottleneck. Even the Lynnfield i5s (Core i5 7xx) which are actual quad cores can be a bottleneck to a 280x on some titles without an overclock.
I wouldn't bother with anything higher than a lower midrange GPU unless you plan on transplanting it to a new build sometime in the foreseeable future.