In June, Intel released its new Kaby Lake-X and Skylake-X CPU architectures based on the X299 platform. We talked about the current flagship 10-core, 20-thread i9-7900X, comparing it to the previous Broadwell-E flagship, the i7-6950X, and the AMD Ryzen 7 CPUs. Alongside the flagship 10-core, Intel released an 8-core, 16-thread i7-7820X, which costs “only” $599, compared to the previous $1000+ of last generation’s i7-6900K. Alongside these processors there are also the AMD Ryzen 7 8-core 16-thread CPUs, costing from ~$320 to ~$499, depending on the model.
The i7-7820X is an 8-core, 16-thread processor running at a 3.6 GHz base, 4.3 GHz boost and 4.5 GHz TurboMax frequency, costing $599. Last generation’s i7-6900K runs at a 3.2 GHz base, 3.7 GHz boost and 4.0 GHz max turbo frequency, costing $1089. The AMD Ryzen 7 1700 is a ~$300 8-core 16-thread Summit Ridge CPU with a 3.0 GHz base and 3.7 GHz Turbo clock on a single core. The Ryzen 7 1700 can be easily overclocked to match the performance of the Ryzen 7 1800X on any $80+ motherboard, so we will use this CPU as a comparison.
As was with the i9-7900X vs i7-6950X, the i7-7820X has a modified cache infrastructure compared to its previous generation counterpart. Instead of 20 MB of L3 cache on the i7-6900K, the newer 8-core now has only 11 MB of L3 cache. That is due to cache re-organization, where Intel started using a similar strategy to AMD, creating a so-called “victim cache,” which improves or hurts performance, depending on the application. For a more in-depth cache analysis you can read the AnandTech Skylake-X review.
Another notable difference between the Broadwell-E and the Skylake-X CPUs is the PCIe lane design. Where the previous generation CPU supports up to 40 PCIe lanes, the newer i7-7820X only has 28. That is a 30% decrease, and for many it is one of the main reasons why the Skylake-X architecture is regarded poorly. Fewer PCIe lanes leads to less expandability options, especially in terms of graphics cards and fast storage devices.
Many sites have covered the i7-7820X, both in terms of professional applications and gaming:
In general, the i7-7820X is a great CPU for productive workloads, offering relatively similar performance to the previous generation i7-6900K for $400 less. An overclocked Ryzen 7 1700 should still offer the best “bang for buck,” though, as it can often be found for around half the price of the 7820X, while being on the far cheaper AM4 platform. It will fall 10-15% behind in benchmarks, but for 50% of the price.
In terms of gaming, the i7-7820X falls somewhere between the gaming champion i7-7700K and the i7-6900K. For a $599 HEDT processor, it fairs very well, compared to the other two CPUs.
In gaming, Intel’s Skylake-X processors fair very well against both the Broadwell-E CPUs and AMD’s Ryzen 7. Intel is very good at competing with itself on all fronts, both in terms of price and performance (this depends more on the application and cache-related behavior now, but is mostly improved). However, when factoring in things such as power consumption, temperatures and total platform cost, the competition from AMD becomes much more stiff. Ryzen processors do not overheat due to the soldered heat-spreader (Intel is still using thermal paste, which is also of poor quality) and Ryzen consumes much less power when comparing performance/watt. The AM4 platform is also far cheaper than X299, and the CPUs do not require delidding or expensive water-cooled solutions to overclock. Even Intel’s previous generation Broadwell-E processors consume noticeably less power than the newest Skylake-X releases.
There is also the looming threat of a $1000 16-core 32-thread AMD Threadripper part coming out by the end of summer, so you may want to hold off from buying into a HEDT platform until then.