The RAM speed is limited by the processor, specifically, not so much the chipset. You can look up your CPU model on Intel's site (ark.intel.com) and see what its memory controller will support.
If I recall correctly, the CPUs for this chipset will support up to 1600 - possibly 1866, if you have a high-end CPU. 2133 is not recommended; it may work, but anything faster than what the CPU supports will downclock to what the CPU supports, and it may even cause instability.