CPU going from 100% to 10%

[MoonOwl]

Hello, I've got a problem with my cpu that has been going on for some time now.
Whenever I play some game that has high usage, my cpu is around 80-90%, then at one moment my game lags and when I look at task manager, the CPU usage is at 100% and slowly gets to around 10%. The game is lagged for that whole time, sometimes even crashes and after that, the CPU goes back to normal...
Temperature is normally around 35°C-40°C, when the game lags, it goes to around 60°C, after it crashes it goes back into normal.
What can I do about it? Is there any way to fix this? Or a completely new cpu?

[VARADHARAJAN]

@MoonOwl 

If you using a desktop, the minimum power state to 100 and the maximum power state to 100 under advanced power settings.

Cleaning 

Always use SSD or NVME disk for Windows
Use the Disk cleanup tool, to get rid of waste files
Uninstall very rarely used applications and software
Dont use third-party antivirus, Instead use Windows Defender
Scan Complete Windows partition
Delete all possible tasks registered under the task scheduler
Disable start-up items under the task manager
Delete or remove all files from the temporary folder C:\Users\username\AppData\Local\Temp
Disable any unwanted services that are set to manual

[MoonOwl]

Power states are set to 100% + I already did a whole windows reinstall onto ssd. Neither helped.

[VARADHARAJAN]

@MoonOwl 

Name of  processor and model,  current version bios installed. Motherboard model