This article explains how to check both the base clock speed and boost clock speed of your computer.
How to Check Your CPU Speed on Windows 10 – Tutorial
The base clock speed is the speed that your processor is guaranteed to run at during normal use. It will usually run faster if it can, but this is the lowest frequency that you should normally expect your CPU to run at.
Windows and macOS have their own built-in methods to check your CPU's base clock.
Type My PC in the Windows search bar.