it would seem that this is by design. [URL]  
Hi, I have a new Dell R640 with Intel silver 2.2 Ghz cpu that is behaving wiredly. Server is running Windows server 2019 and task manager is showing that the cpu runs on 2,67Ghz.  When I apply load on server ( prime95 torture test ) the cpu frequency goes down to 1,6Ghz.  Returning to 2,67Ghz as soons as load stops. Server bios is set to performance profile and latest bios is installed 2.6.4  I did open a case with prosupport but the technician seemed to think this is a software problem. Have any of you seen similar behavior? Also if i disable turbo boost cpu will run att 2,2Ghz when idle but drop down to 1,6Ghz if loaded.   Cpu is Intel(R) Xeon(R) Silver 4214 CPU @ 2.20GHz    
R640 server CPU running at 1,6Ghz , Xeon(R) Silver 4214 CPU @ 2.20GHz