I only have my i7-920 OC'd to 3.8 and the memory underclocked at 1810MHz and at full stress, my temps get upto 76C. When I try to go 4.0 or raise the memory closer to its rated 2133, my temps spike to low to mid 80's.
Your memory might be rated at 2133mhz but that is overclocked and even at 1810 it is still overclocked. Anything above 133mhz is overclocking as the fastest specification by JEDEC is 1333. So you will be producing quite a bit more heat from the memory as wel as the processor. The i7 s are good heat generators anyway and don't need any excuse to get hot.
All you can do is to make sure that you have a good airflow through the case and radiator. It might help to put a dedicated fan on the memory to help with that side of ikt.