There are two possibilities:
1. The CPU is auto-throttling to a lower speed to protect itself from heat damage. This would only apply if the core temps are in the mid-90sºC.
2. The Turbo Boost Power Limit settings aren't high enough. Switch it to Manual. Change the Short Duration PL to 220 and the Long Duration PL to 200. Change the Long Duration Maintained to 56.
Edit: lol just saw your other post, where you already changed to higher numbers.