The problem is gone for me, it’s fixed with latest nvidia driver. Frametime is really smooth now on ultimate gpu mode.

Nice, now there is only this problem left https://rog-forum.asus.com/t5/gaming-notebooks/rog-strix-scar-18-gsync-and-screen-off-will-balck-screen/td-p/943531

That buzzing sound is coil whine, pretty much every device has it to some point. I wouldn’t worry about it. 

There is also this gsync black screen issue that you probably don’t know that occurs when the device goes to sleep https://rog-forum.asus.com/t5/gaming-notebooks/rog-strix-scar-18-gsync-and-screen-off-will-balck-screen/m-p/944574   For some of your i...