As I'd already spent my own money on the Asrock X99 Extreme 6 motherboard, DDR4 RAM, et cetera, it was just a question of swapping in the chip (an engineering sample). And by "swapping the chip," I mean removing the old processor, scraping off the dried-on thermal paste, applying a new coat and installing the new one. An hour later, I had probably the fastest computer within a 15-mile radius (though to be honest, I do live in rural France).
Intel's eight-core chip can be overclocked easily, but I didn't try to push it as much as I did with the six-core i7-5820K. That's because the i7-5960X starts at a lower clock speed than the i7-5820K (3GHz instead of 3.3GHz) and has more cores, which generate more heat. As a result, the X model is generally considered a bit harder to overclock than the K models. Instead, I merely put it in Turbo mode and left it at that. Doing so bumped the memory speed to the 2800MHz maximum and pushed the 3GHz CPU up to 4GHz. I deemed that acceptable, because I want to use it as a regular video editor or 3D artist would, not an overclocking freak. As much as I'd like to play with liquid nitrogen and all.
So now what? The first step was to test the chip in various benchmarks.
Suffice to say, it's a good deal faster than any other Intel Core i7 chip, and would beat a lot of Xeon CPUs, too. However, it wasn't much quicker than the six-core chip in benchmarks, thanks to the fact that I was able to overclock the 5820K model more, as well as the lower temps.
It's in real-world use where things gets a bit complicated. For users of Adobe Premiere Pro CC, Autodesk 3DS Max and similar software, the eight-core chip frankly doesn't offer much of a gain over the cheaper six-core model. That's because all of those content creation products now lean heavily on the GPU, and in some cases you'd be much better off spending that $660 on a high-end NVIDIA or AMD card. Also, making software that uses multiple CPU cores efficiently is a tricky business, so some testers feel that it's not worth the expense for such chips.
To cite one example, I rendered a 3DS Max 2015 scene in 14 seconds on average per frame with the eight-core CPU. With the six-core model, it took 17 seconds -- not exactly a $700 improvement. That's because 3DS Max's software now uses your NVIDIA GPU to improve speed with its default "Mental Ray" renderer. On its blog, Mental Ray says that global illumination -- a very time consuming part of a render -- is now done by the graphics card. In one example (above) it said that the GPU reduced the scene render time from 13 hours to 37 minutes.
The same applies for gaming, in case you had the budget for a $1,050 processor instead of, say, three Playstation 4s. Most test sites agree that you'd be far better off spending that cash on a better graphics card setup than on the CPU, which minimally affects gaming performance. Why? Not only are most games not efficiently multithreaded, but most of the hard work is done by the GPU anyway. My own tests confirmed that I saw zero difference playing Crysis 3 on the 8-core versus 6-core machines.
So should you stretch your budget (a lot) for those two extra cores? Nope. If you're an independent graphics or 3D artist with budget enough for Intel's consumer i7-5960x, but not enough for, say, a Xeon CPU with much greater speeds, then maybe you could justify it. Everybody else would be better off getting the 6-core 5820K (or eking the slightly pricier i7-5930K) and overclocking it as much as possible. Then, take the money you saved and splurge where it really counts -- on a graphics card like NVIDIA's Titan X or the AMD Radeon Fury X.