Windows 10: Why does my entire computer drop to 1 frame per second?

Hello, I am having trouble with my computer as of late. I have a custom-built PC that has been running everything fine for more than 3 years now and was going to be a 4th when as of late I have been having issues with prolonged usage. Basically, after let's say an hour or two of playing games not even "demanding to run" games, my whole computer drops to 1 frame per second but my audio is still working. I would only have spotify, discord, steam and the game I'm playing open and mid game it'll just drop to 1 frame per second. I've had frame drops in games before but my whole computer dropping

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locked frames while gaming on second screen after creator's update

after the creator's update when i try to game on my second screen it locks the frames at 60, every time i drop a frame it lowers in steps of 10 until i'm stuck at 40-30. this is not the case when just playing on the screen of my laptop. Love some help to
unlock the frames on the second screen as well, thank you.

 

Frame drops

I have been having terrible frame drops playing fortnite on my hp omen dropping from 120 to 30 randomly, tried reseting my computer didn't work. Does any of you have the same problem or better yet a solution. Thanks!

 

Gaming Frame Rate Drop

I was monitoring the VRAM usage with GPU-Z. In Battlefield 3 there was a scene that a tank was shooting at me every 2-3 seconds, so the frames were dropping a lot, however GPU-Z was not showing any usage above 1800 MB.

Also when the frames drop the coil whine disappears for a second (suggesting that the card is not working that hard), so can it be another component that is bottlenecking it?

In the same time when I first installed Far Cry 4 it was running at 70 fps, whereas now it won’t go above 40 fps, therefore I suspect it may be a defective component.