If theres one thing that I learned while building my computer is that most games nowadays don't even take advantage of the full 4/6 cores and that a dual core is efficient enough if you are gaming. Since I doubt you want a dual core I think you should definitely get a 4 core and ramp that GPU up since if you get a bad gpu + a 6 core that would create a bottleneck on your cpu. So you should go with the 4 core + better gpu. A good gpu is necessary and probably more important than the type of cpu in gaming.