Weird general lag

[Erundil]

Hi, so i've been getting these random lags that last for a good minute or 2 at a time where literally everything just lags, dragging windows, typing, videos, it's like the whole pc slows down to 10fps then after a while it goes back to normal.

The weird thing is that i can't really tell what's causing it, i thought it was the new Firefox Quantum that i've installed but even if i use Chrome again it happens anyways, the temperatures are fine (CPU is at 40/45C when doing normal browsing/watching netflix), at first i thought that my cpu was just nearing its death, but even in the task manager the CPU usage rarely goes above 70% and during those lags it's usually between 40 and 70, memory is usually under 30% while browsing and the disks are fine, so i can't really tell what's causing this, even when i play games and the system is under stress everything is fine.

I was hoping to at least be able to put a patch on the problem until January when i'll be upgrading everything but the GPU, so does anyone have an idea of what might be causing this?

My CPU is an i7-4770k at 4,5Ghz and my GPU is a gtx1080 Strix, psu it's be quiet 750w, 16GB of corsair ram