nomenclature scheme of the updated Z390 mainstream lineup:
Intel Core i9-9900K (est: 8 Core / 16 Threads)
Intel Core i7-9700K (est: 6 Core / 12 Threads)
Intel Core i5-9600K (est: 6 Core / 6 Threads)

https://wccftech.com/intel-core-i9-coming-to-z390-mainstream-platform-core-i9-9900k-flagship/