http://www.hardwarepal.com/best-cpu-gaming-9-processors-8-games-tested/
ARMA 3 is an unoptimized mess, and RTS like SCII tend to benefit from better CPUs, so unless you mainly play the latter, ignore those.
http://www.tomshardware.com/reviews/gaming-processor-frame-rate-performance,3427.html
as i said, while there's a fall in performance, in some but not all games, it's really nothing to major. performance is still within acceptable range. here's my personal CPU usage with an i5-3330 (3.0-3.2ghz) with 670:
no bottleneck and good enough to justify me getting a 780ti if i could even be bothered. i plan to stick with this for another 3-4 years, if the building bug doesn't bite me again (i had an i5-2310 + 6870 before this), my next probable upgrade being a GPU in 2-3 years. an i5-2400 is still a good CPU for gaming, and really there's still no worthwhile upgrade from it, not for $200+. there's a good 2 years or so from that CPU at worst.
getting a 4670K with an H81 is basically overpaying for a feature you completely under utilize. for around $300, do you really think a 10-15% gain at most, in a few handful of games is worth it, when you could spend it elsewhere like a better GPU (if you don't have a good one at least) and see more gain from there?
(no gaming comparison between a 2400 & 4670K, so have a 3570K instead. for comparison, a 4670K really isn't an impressive upgrade from a 3570K. it's only really recommended for those starting a new build)
http://www.anandtech.com/bench/product/363?vs=701