the cpu usage on the Performance tab is not consistent with utitilities or the usage shown on the Details tab, this is a known issue where the performance and processes tab takes boost clocks and core count awake and used into account when factoring usage, because it factors these into things, the usage on these tabs are usually higher than the Details tab.
For the clock reading on task manager and aida64, you need a power profile that has the min cpu state set under 100% to report correct idle behavior
having min cpu state in the power profile maxed out to 100 will show constant max clocks in aida64, task manager will show up to 200mhz range from max clock
HWInfo will show max actual clock, and low effective clock.