Hello. Open TS and click on the TRL button. This is Maximum Turbo Ratio Limits you can see there what is your Ratio Limit for 4 active cores. That means if application uses all 4 cores your Turbo Boost limit is not 2,9 or 3,1 GHz but 2,6 or 2,8 GHz. If there is only one thread for only 1 core then that single core can make 2,9 or 3,1 GHz. Simply told: More active cores = higher ratio limit. You will see this in TRL menu under 4 active cores. As I can see your limit for 4 working CPU cores is 26 Multiplier = 26 x 99MHz = 2,6GHz maximum Boost. You cannot change this limit, this is how your CPU works.