Both have 8 heat pipes and about the same surface area to dissipate heat, but the 412 can accommodate dual fans (push / pull) configuration. I'd pick the 412 for max air flow if you have a low air flow case.
On the other hand, I'm from Texas so the bigger the better. If space isn't an issue (180mm), go with the CM V8. I have it installed on an AMD 8350 8 core 125w and it has yet to spool up to full speed to keep it cool under load.
Ahhh alright thanks mate I've got the Arctic Freezer Xtreme Rev.2 , is it worth the change ?
I have the 212 evo and it also can be set for push/pull too but the 413s is larger. I've read on other forums that the 212 evo has better performance. I'm currently running an i5-3570k OC to 3.7ghz idling at 28 degrees Celsius with the push/pull config.