Clock speed drop

[kamrandar413]

My PC's clock speed is 2.00 GHz and a couple days ago it became really laggy so I checked it in the task manager and it showed that the clock speed was 460 MHz
What caused this drop?
If anyone can help please do

 

[Barty1884]

Please post your full system spec.

Are you monitoring temps?

Clock speeds will throttle hard if you're overheating.