From all reviews I have read, Multi threaded applications (Like Sh5) run better on the AMD Phenom II x6, because they utilise all six cores.
This one from CPU-World.com shows that the Un-overclocked Phenom II runs Slightly better.
http://www.cpu-world.com/Compare/372...5_i5-2400.html
My AMD Phenom II X6 runs at 4 Ghz like a breeze, no problems, the doesn't even need to spin up for more demanding games, like Sh5, Crysis 3.
The Phenom II (Tested by me) can run Crysis 3 at 90-150 FPS solid and they core's ave not even got over 50%.