Particularly in case of Threadripper, they use cherry picked binned cores so they can actually hit even [slightly] higher clocks than their mainstream cousins.

We don't know the Threadripper 2's clocks yet, but last gen TR 1950x could hit 4.2Ghz with Turbo, while the best mainstream Ryzen the 1800x could do 4.1Ghz with Turbo.

The Ryzen 2 top dog right now can do 4.25Ghz with Turbo.. so we could perhaps expect TR2 to hit 4.3Ghz+ on Turbo.