The extent of a "CPU limitation" depends on what games you're playing and what resolution you're playing them at. MMO games like Starcraft II and Skyrim can show CPU weaknesses pretty well and lower resolutions put more weight on the CPU to keep up with the GPU. Here's a good article to read
since it compares many CPUs in a variety of games.(they use a 7970 to elminate GPU bottlenecks) At the end of the day though, yes, you've got a good enough CPU to enjoy the frame rate bump of a new GPU.
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