I have 2133 gskill ram with same board and cpu as well but I couldnt go past 2133 without pushing the voltage alot and I also ended up backing off on the speed from 2133 to about 2090 after a couple weeks. During gaming sessions I would get errors. Its hard to say whether it was a limitation of the ram or the cpu....Andre can you post your ram voltage and timings?
I was also able to push it up to 2400Mhz with slacked timings 12-12-12-32, but it wasn`t always very stable. Mind you the system felt a lot more responsive, especially with the NB frequency up to 2200Mhz.