Buying parts for a new computer - want to find gpu/cpu equilibrium

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http://superuser.com – I am looking to get two GTX 760 for a new PC and want to know how strong of a cpu I should get to prevent a bottleneck from the cpu. I have found a lot of information online on finding what causes bottlenecks on existing PCs but I havent found anything that can give me an idea as to how the strength of cpu and gpu should scale together. Can anyone give me any idea or a link to a website that provides this kind of information? (HowTos)