In my test i made 3840x1440 and i couldn't move the mouse to the top of the screen. It looked like native 1440p with no scaling. I think this is the solution. If it is, I couldn't find this answer on youtube, maybe it's too obvious to make a video.
I just tried "Custom Resolution" in the NVIDIA Control Panel. I think it may work, but i can't test it until i organize the cables out of my GPU fan in a few days.]
I wonder if there's something like that for AMD users.
I have a BenQ BL2711U 27" 4K IPS Monitor. 1080 Ti.
How can I game at 1440p with black bars on the edges instead of having the image scale to the full size of the screen?