I will link the 8700k benchmarks for reference below. Once again, I must reiterate, you see the 8700K at 4.7 boost vs a 7700k at 4.5 boost losing. Moreover, you must consider the heat output of six cores is greater than four as well as the electrical resistance.

This is an impact to single core performance. The data has to travel a greater distance which increases latency and begins to starve cores for bandwidth. Moreover, when you add more cores to the ring there is still a latency hit vs a four core part on a ring bus architecture. The mesh architecture, while seeming to have high latency, is actually much lower than it would be if they used the old ring bus interconnected method like we saw in the Xeon E5 v4. The newer Mesh technology while having higher latency than ring bus topology does not have the same latency as a Ring Bus based processor with greater than eight cores. Single-core performance benchmark, the SuperPI 32M gives another crown to the Intel platforms, with the Core i7 7700K scoring the lowest time thanks to the high stock clocks. At similar clocks a Core i7-6800K basically matches Ryzens CB R15 score and beats it in Fritz Chess with less cores (6C/12T vs 8C/16T). Intel continued to advance the ring bus beyond eight cores in Xeon models but was required to utilize two rings and therefore vastly increased cycle time and latency resulting in bandwidth starvation. Fritz Chess is one benchmark where the Intel platform is taking the lead and there is a difference between the Ryzen 7 1800X and the Ryof about 2000 points. 0-20 faster than Core i7-7700K in MT applications means its a solid product, but Intel probably still dominates per core (ST) performance and would holds its own in many scenarios. The Core i5-8600K manages to gain a lead of around 200 points over 7700K whereas the single-core performance is almost identical with a difference of 25 points. Things do, however, change when it comes to CPU-Z. In essence, it is limited to eight cores. Same is the case with Fire Strike and Fritz Chess benchmarks where it lags behind the 7700K by a slight margin. The Ring Bus can handle up to eight cores before it begins to lose efficiency. The reasons for this is explained by understanding the Ring Bus architecture that was brought about during the Nehalem era. That means while the 8700k is boosting 200mhz higher it is still losing. The 7700k is clocked at 4.5 out of the box for single threaded whereas the 8700k boosts to 4.7. While the loss is not major it is, in three different benchmarks, losing in single threaded work loads. Hear me out, in recent leaked benches the 8700k is showing a slight loss to the 7700k.

Fritz chess benchmark 7700k