I am thinking to buy a 5870 or 5850 for gaming instead of upgrading to a 1156 platform. Right now i have an E8400 E0 and a HD4870 512 MB. How much should I OC my E8400 so it won't bottleneck a 5870 or 5850? I use my PC for gaming, Internet browsing and watching movies. No program that require the power of a Quad.

*I use 1920x1080 resolution.