Furthermore, we learn the Core i7-9700K eight-core, eight-threade CPU will have a 4.9GHz single-core Boost and 4.6GHz Boost with all eight cores in use.
VideoCardz also has some 3DMark performance details:
We also have our own leak comparing two upcoming processors: i5-9600K and i7-9700K. There is a minimal difference between the two SKUs in 3DMark Fire Strike Ultra when GPU performance is considered, but Physics Score is 36.8% better on 9700K.