i9-7960X - Intel Core i9-7960X 16-Core 2.80GHz 8GT/s DMI3 22MB L3 Cache Socket LGA2066 Processor

When the number of CPU cores actively working increases, the speed they run at needs to be decreased to stay within the power and thermal limitations or stability is compromised. This is why 16-core / 32-thread chips like Intel's i9-7960X has a base clock speed of as low as 2.8 GHz for all cores, with a turbo-boost v2 of 4.2 GHz when working with a single thread workload. It is also why we see a 4-core / 8-thread chip like the i7-7740X with a base clock of around 4.3 GHz and only a small turbo boost up to 4.5 GHz.