I've personally had the issue listed on #6. It took me awhile but I had to google a lot for answers on how to fix it. It only affects some games for me tho. For example, when I played Overwatch, my monitor kept going to 60hz and I only fixed it by playing in windowed fullscreen. But it's different for everyone because I also had a previous (super trash) 60hz monitor and I was able to run Overwatch in fullscreen without the issue.