Hi Snake, there is no such thing as an 4930k, and there are no 3rd or 4th generation 6 core CPUs available on the market yet.
I hope you mean 2nd Generation Sandy Bridge-E, which has a 3930k.
(note that Sandy Bridge-E is for video editors and professional use, Haswell is more optimized for gaming)
Regarding motherboards, it depends on what you need.
Do you want to have extreme overclocking, good looks, or just something thats a good value?
Do you have a certain budget?
I personally would however wait until the 3rd Generation Ivy Bridge-E processors come out however, as there will be performance improvements and new motherboards.