Building a system like this primarily for gaming is somewhat pointless, mostly due to the fact that no game really uses more than 4 cores effectively, and this is the same reason that Core i5 and Core i7 processors always seem to deliver very similar numbers in all our gaming performance benchmarks. Therefore, it stands to reason that a Sandy Bridge Core i5 processor will deliver similar performance to the Xeon E5-2670, rendering the Xeon(s) overkill and thus somewhat pointless. In fact, an overclocked 2500K would almost certainly deliver better performance in any game on the market today. Still, for casual gamers (that do a lot of video editing, for instance), the Xeon E5-2670 processor might make sense, even one on an X79 motherboard would work well for this purpose, as we are about to see.
The Witcher 3 Wild Hunt is a CPU intensive game. Despite this, we only saw 10 - 20% utilization on the dual Xeon E5-2670 setup. Just 3 of the 32-threads were heavily used, with half a dozen others working at around 20% or less. Naturally, removing one of the E5-2670 processors still left us with 16-threads, so no decline in performance was seen. Overall the E5-2670 allowed the GTX 980 Ti to deliver similar performance to that of the 5960X and 6700K in this title as we were primarily GPU limited. Had we reduced the in-game quality settings and disabled HairWorks, the 6700K would likely have become noticeably faster than the E5-2670, but that doesn’t exactly simulate realistic use at this level of performance.
The Xeon E5-2670 provided a similar minimum frame rate to that of the Core i5-4690K and Core i7-5960X, though the average frame rate was slightly lower. Again, as expected, adding a second E5-2670 did nothing to aid performance.
Lastly, we looked at the performance of Grand Theft Auto V. Here, the Xeon E5-2670 did slip behind the newer Haswell and Skylake processors by a considerable margin. Still, keep in mind that we were using a GTX 980 Ti at a relatively low resolution. Therefore, a lesser GPU or a higher resolution would close that gap up - most likely to a negligible margin.