The folks over at OCWorkbench were lucky enough to have witnessed a Sandy Bridge-E processor being overclocked earlier today and kindly shared some details that help give us an idea of how well these chips will clock up.
The specific LGA2011 Core i7 model used was not mentioned, so it's possible it was only a quad core offering. Alas, using a "regular" air cooler it still managed to cruise along just shy of 5GHz (4.92GHz to be exact) with its idle temp holding at 45c.
This was made easily possible via the BClk that can be increased on Sandy E without any dramas. This particular result was achieved by setting the BClk to 120MHz, using a multi of 41X and a core voltage of 1.51v. As for the memory, this was DDR3-2400MHz RAM with a CAS latency of 10T.
This is certainly a very good sign when considering the substandard, generic air cooling solution used here and that even with the best air cooling solutions on the market paired up on existing Sandy Bridge LGA1155 processors, 5GHz is no mean feat.