Sudden low performance

[Nuclearius]

it's been around 1 or 2 weeks by now, i suddenly started having low performance in games, Rainbow six siege is the best example, i used to play around 130+ FPS, but suddenly i went to 45-60 FPS, forcing me to play windowed to be able to play; reinstalling geforce experience and the driver improved the performance, R6 was running 80 FPS but not stable, I tried setting to prefer max performance, didn't work too, reducing graphics didn't help too; I believe it's the graphics card because i noticed the GPU is being a lot less used on fullscreen, the temps seem to be normal.

my setup:
windows 10 pro
cpu: i7 6700k
gpu: ASUS GTX 1080 ti
Motherboard: ASUS Z170-A
the setup is pretty new, got it this year

i tried:
reinstalling geforce experience and the driver
setting power management to max performance
reducing graphics quality in the games

thanks

 

[Nuclearius]

after resetting windows, it seems things got better, GTA still getting lower performance, but BF2 and other games seem to be fine

 

[Nuclearius]

maybe open world games in general, CPU and memory maybe?

 

[Nuclearius]

it seems like the reset may have increased the performance for a while but it seems to have gone back down, yesterday in For Honor but FPS suddenly went down to 60, and it stuck there sometimes going under it, restarting the game sent it back to 140, even in 140 sometimes i have these drops below 60, but that time it got stuck in 60 instead of going back up, i will see if it happens in other games