To elaborate on this, the processor is guaranteed to function correctly at turbo speeds (while overclocking has no such guarantee) but Intel doesn't guarantee that turbo frequency will be reached all the time. The more intense your code, the lower frequency you get. Fortunately most server code is integer-only and has low IPC so it should hit 4.0 GHz.
> What is Intel® Turbo Boost Max Technology 3.0 and how does it work?
Intel® Turbo Boost Max Technology 3.0 uses a driver coupled with information stored in the CPU. It identifies and directs workloads to the fastest core on the die first. The driver also allows for custom configuration via a whitelist that enables end users to set priority to preferred applications. The driver MUST be present on the system and configured correctly, as current operating systems can't effectively route workloads to ordered cores.
