i have an AMD Phenom II x6 1100t overclocked @ 3.8 ghz. i wanted to upgrade my GPU from a 6870 to a 7970 by june. i have THOUGHT about upgrading my system (new CPU +motherboard, going for the ivybridge or sandybridge-e 3930k) but my laptop is going to need to be replaced soon and i can't throw all my money into a new system.
my question is whether or not if i JUST upgrade my graphics card, will my CPU be a bottleneck to the point where the performance increase will be so little it won't be worth it?
No,because Skyrim is more sensitive to clock speed than the no of cores.Also it performs better on any Intel cpu than AMD.
So there will be some bottleneck in a few ill-optimized games but you have nothing to worry about because the frame rates will be much higher than 30fps despite of bottleneck if you have a good GPU.
Therefore I suggest that you upgrade to 7970 becuse gaming depends mainly on GPU not cpu.