Benchmarks: CPU II
The benchmarks on this page are all about stressing the maximum number of cores. Given the Core i9-9900K's ability to run at 4.7GHz on all eight cores, it is no surprise to find it challenging the 10-core Core i9-7900X.
Intel has the fastest eight-core, 16-thread processor on the market, but it's important to note that the average multi-threaded performance gain over the Ryzen 7 2700X isn't huge.