Ahead of their launch later this quarter, SiSoft SANDRA benchmarks of Intel 8th generation Core i7-8700K and Core i5-8400 six-core processors surfaced in benchmark databases, which were promptly compared to their predecessors by HotHardware. The results put to the test Intel's claims of "over 40 percent more performance" compared to the 7th generation Core processors, which the company made in its 8th Generation Core Launch Event presentation. A bulk of these performance increases are attributed to the increasing core-count over generation, which directly yields higher multi-threaded performance; while a small but significant portion of it is attributed to increases in single-threaded performance. Since the "Coffee Lake" micro-architecture is essentially a refresh of the "Skylake" architecture, single-threaded performance increases could be attributed to higher clock speeds.

The Core i7-8700K is the top-dog of the 8th generation Core mainstream-desktop processor family. This six-core chip was compared to the product it succeeds in Intel's MSDT product-stack, the quad-core Core i7-7700K. There is a 45 percent increase in performance, in the "processor arithmetic" test; and a 47 percent increase in the "processor multimedia" test. These two test-suites are multi-threaded, and hence benefit from the two added cores, which in turn add four additional logical CPUs, thanks to HyperThreading. "Processor cryptography" sees a 12 percent increase. The single-precision and double-precision "Scientific Analysis" tests, which again are multi-threaded, see 26 percent and 32 percent performance gains over the i7-7700K, respectively.