SmartGeek :
See, if this Six Core processor is giving 70% load when gaming, then the four core Ivy Bridge will run on 100% load.
Apples to oranges, to put it lightly.
Intel chips are vastly more efficient, resulting in a much higher IPC (instructions per cycle) and better performance at any given clock speed. Plus the 3570k is clocked higher anyway. A four core Intel chip is in no way equivalent to four cores of a six core AMD chip, and this kind of comparison is beyond meaningless.
Also, 70% load doesn't necessarily mean four of six cores maxed out. It could well be six cores that aren't being fully utilized, or three maxed out and three more not fully utilized, etc. It will entirely depend upon the game and how good it is at splitting its tasks up across different threads. You also can't just look at the task manager to figure this out, because threads regularly switch between cores in most cases. Usually, all cores will report similar usage, even when running extremely unbalanced threads. To really figure it out, you'd need to look at individual threads and how much CPU time they use relative to each other.
A lot of games get some easy parallelism by offloading simple tasks like audio to other threads, but these threads might only occupy 10% of a core's available time slots. Other games are much better and divide up the work more efficiently, resulting in several threads which can really hammer the CPU.
My advice to the OP is to go look at CPU benchmarks for the games you're interested in and see if there is extra performance to be had for going with a faster four core processor over a six core. For most games, there will be little to no benefit, but for some, you might get noticeable gains.