[benjaminl]

Intel -E platforms share more with Intel's Xenon for servers than they do their consumer chips. The Broadwell-E based on the Broadwell platform so always lags behind the consumer release of the platform.

This chip isn't designed for consumer workloads, so you wouldn't see much improvement if it was in your iMac, but is a nice improvement over the previous Haswell -E platform.

While it may seem on the surface that compared to the non-E version they just added a couple more cores. But the changes go deeper, for example the Broadwell-E i7-6850K has almost doubled the amount of cache, doubled the max memory to 128 GB. But more significantly, for some workloads they doubled the number of memory controllers from 2 to 4 and increased the number of on chip PCIe lanes from 16 to 40. This increase in memory bandwidth and PCIe lanes allows for the creation of monster multiGPU data processing computers.

Here is a comparision between your iMac's CPU and the new Broadwell-E i7-6850K. As you can see it is really an Apple and Oranges comparison: http://ark.intel.com/compare/94188,88195