This is the leaked table by GIGABYTE last week disclosing core speeds of AMD's FX CPUs.
This slide from DonanimHaber now shows the expected Turbo Core speeds of each FX CPU.
It was expected a fair few months ago that the 'Zambezi' CPUs will excel up to 4.2GHz via Turbo Core and it would seem that the FX-8150 will do exactly that. With the FX-8120 hitting 4.0GHz and the FX-8100 up to 3.7GHz.
The FX CPUs are expected for release sometime this month.