Sandy Bridge memory controllers are quite capable of running 2133mhz... Unlike Nehalem, SB does not require a difference of 0.5v between memory voltage and VTT (or sometimes other boards call it VCCIO/VCCSA/System Agent).
Stock voltage on this is 1.0v, for 24/7 usage you should only run about 1.2v max. From what I've seen you should need between 1.1v - 1.15v for 2133mhz, but of course every CPU varies so you're going to have to test for yourself and optimize the voltage. Just stay at or under 1.2v and you'll be golden.
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