The GPU up-scaling option literally does nothing, I can't play my games in 4:3 and stretch them now as it doesn't work.
I've tried the Windows 8.1 15.6 beta driver, all the way to 15.7.1 Windows 10 driver.
How do I fix it/
I have the opposite but related problem as I can't get GPU upscaling to stop working. If I change my resolution from 3840x2160@30 to 1920x1080@60, it continues to send a 3840x2160@30 signal to my monitor that appears to be upscaled from the 1080 image.
This has only happened under windows 10, and I can find no way around it.