As most Phoronix readers know, the C-Ray test is a favorite open-source multi-threaded ray-tracing benchmark. At stock speeds the i7-3960X was not any faster than the i7-990X, but when overclocked the performance improved by several percent.
Smallpt is a very lightweight OpenMP path-tracing test. The Core i7 3960X Sandy Bridge-E did better than the Gulftown Extreme in its stock configuration and obviously improved further when overclocked.
The Sandy Bridge-E also easily wins in the TSCP chess compute benchmark.