According to various leaks ( http://wccftech.com/intel-broadwell-e-core-i7-6950x-price/ ) and ( http://wccftech.com/intel-broadwell-e-hedt-computex-2016/ ) the CPU frequencies of the upcoming Broadwell-E i7-6000 processors are as follows:
CPU Cores Frequency Turbo-boost L3 Cache
i7-6950X 10 3.0 GHz 3.5 GHz 25 MB
i7-6900K 8 3.2 GHz 3.7 GHz 20 MB
i7-6850K 6 3.6 GHz 3.8 GHz 15 MB
i7-6800K 6 3.4 GHz 3.6 GHz 15 MB
Observe how, for the top 3 processors, as the core-count increases, the CPU frequency decreases. While the L3 Cache increases - as it's shared between all cores it works out at 2.5MB/core.
Most of my computing needs are not many-core optimized, such as games - I don't do things like video-encoding, rendering, or bitcoin-mining - which means whatever is in cache would be suited to however many cores are being utilized, so the larger L3 cache would definitely help (and so be effectively larger than 2.5MB/core).
So my question is: if I got the i7-6850K, would the extra 600Mhz (300Mhz in turbo-boost) in single-threaded performance offset the smaller L3 cache compared to the i7-6950X? But contrarywise: would the 500Mhz turbo-boost in the 6950X be in-effect if I was running low-threaded programs and augment the larger L3 cache?
To be sure for certain, I'd have to wait for the Broadwell-E benchmarks to come out - though ideally I'd like to get my pre-order in first.