What driver version are you currently using? Over the years nVidia has released some faulty drivers for their products. Some time ago, I remember there were many cases of people having their gpu clock speeds being locked unreasonably high whether the computer was under load or sitting idle. Another time, I recall there was a similar issue that affected many owners of high hertz monitors. Have you ruled out a faulty driver being the root cause of your issues? Have you rolled back your driver a couple versions down and seeing how your card behaves then? I recommend checking the r/nvidia subred