if you set speedshift to 0 it will maximize your cpu clock speed which means, on the contrary youre gonna use your cpu with turbo at higher frequency. theres two options you can do to prevent turbo, either you can go to power settings/change plan settings/advanced settings/processor power management and then set your hightest processor state as %99 or %98, whichever prevents the turbo, you can just see your frequency at task manager, if %99 doesnt work try 98 cuz mine was like that.
and the other option is more usefull, which i was also using too, a reg file which provides you an option about how would you like to use your turbo boost, you can just choose disable from there, it will be shown in the same place as i told above