You should be aware that Zambezi Turbo mode is not that simple. There is 2 "main" levels of Turbo. For example, a 3.6 GHz base CPU can reach 3.9 GHz with all cores used as long as TDP remain under a specified value AND can reach 4.2 GHz in single core mode. So, depending on the usage on a 8-threads application, you can be at 3.6 GHz or 3.9 GHz.