Windows 10: Low cpu usage and sudden frame drops in games

I play Valorant on my i9 MacBook Pro by installing Windows on it via Bootcamp. I have been playing games on it without any problems on 60fps for almost 5 months now. It has AMD Radeon Pro 5500m gpu. Recently though I have noticed that my game gives loads of frame drops when I try to engage in combat, it even goes down to 10fps and makes it very laggy and difficult to play properly. I think there is some problem with the gpu not working as it should because when i contacted valorant they told me from my logs that my gpu drivers arent updated even though I have installed the latest driver from A

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Low frames on Gaming PC

Hey

My MSI GE72VR Apache Pro, laptop just started to have Counter Strike: Global Offensive frames drop to around 35. My frames have went from around 250+ to then 60 then to 35 frames. I don't know whats happening getting my computer maintained and dusted helped
a bit it made the frames go from 60 to around 80 for a bit then it dropped down to 35. In Rust I've been getting 11 frames. Most of my games are unplayable at this point. My in game temp is CPU 83 Celsius for games like Rust. and GPU is around 65 Celsius.
I'm pretty sure i'm getting temperature throttled but I don't know what to do. Please help.

 

Sudden FPS drop/Stutter

Since 2 days ago, I just turned on my Computer, and it starting having issues while I was playing Witcher 3 (starts with decent fpsm and then very low fps, dropping to 35, then 20, and stopping at 12 or so, in a matter of seconds, in a matter of 1min of starting the game), also stuttering without any high demanding programs, randomly. I was playing at 45-60 fps, without any stutters or sudden fps drop. Have tried other games the issue persists. Even setup everything to low settings.
I have ran several tests with several tools, all seems normal, no sudden memory spikes, or temperature raising out of the ordinary, nothing that would indicate such an fps drop or stuttering.

MSI Afterburner

I also did the reset option on Windows10, completly cleaned out all my personal info from the windows partition.
So at this point, I am not sure if it is a software issue or a hardware issue.
Any suggestions are greatly appreciated.

Edit: I kept doing some tests to find out the issue. And this happened before and I was able to replicate it. Same thing happened as before, till I set it up to fullscreen, Alt+Tab from the game and then back to the game, FPS went up to 50 again, stable and good, dropped after a couple of seconds. After a bit it went to 2-5 fps, and I had to shutdown the game, because even the sound was getting messed up.

MSI Afterburner 2

In this image those ups and downs in the GPU usage are when the fps dropped really hard and the sound got messed up.

 

Dropping frames on videos and high CPU usage after update to 1709

I performed clean install. I even found out that my Windows 10 was running on legacy bios. Used MBR2GPT, reinstalled with UEFI. Everything is smoother now. Dropping frames is gone from edge but still an issue in chrome but only in fullscreen mode now.
High CPU usage is gone too.