Any time we test one of Intel’s thousand-dollar showpieces, we acknowledge its gravitas, all the while contending that most enthusiasts prefer to spend less and lean on their technical acumen to maximize performance through overclocking. In the case of Haswell-E, only the Core i7-5960X is an eight-core model. Buying one of the lesser models means cutting a couple of cores and some cache, at least.
Fortunately, games typically don’t penalize you for dropping from eight to six cores, particularly when you’re running on Intel’s efficient architectures, and doubly so when frequency increases at the same time. As a result, the Core i7-5930K is a better candidate for gamers with money to spend on ultra-high-end hardware. It’s based on the same physical die as the -5960X. Intel simply disables two cores and 5 MB of shared L3. What remains is six cores, 15 MB of last-level cache, all 40 lanes of PCI Express 3.0, and the quad-channel memory controller. Base clock rate jumps to 3.5 GHz, while the peak frequency, controlled by Turbo Boost technology, increases to 3.7 GHz. The Core i7-5930K is priced at $583, potentially "saving" you more than $400.
If that’s still a little rich, the Core i7-5820K lands at a palatable $389. It too is a six-core chip with 15 MB of shared L3 and a four-channel DDR4 controller. However, Intel lops off some of the PCI Express, exposing 28 lanes instead of 40. Frankly, that’s not a particularly painful wound. It leaves lots of room for single-, dual-, and even triple-card graphics configurations, so long as AMD and Nvidia certify x8/x8/x8 arrays. The official word from Intel is that the -5820K supports bifurcation of its lanes into that arrangement; however, the breakdown has to be enabled at the motherboard level.
The Core i7-5820K does lose some frequency compared to the -5930K: its base clock rate is 3.3 GHz, while Turbo Boost accelerates as high as 3.6 GHz.