I've been using nVidia DSR for downscaling for years now. I use 4x scale factor with smoothness set to 0%. When I was on a 16:10 1920x1200 monitor this yielded the 16:10 version of 4K, 3840 x 2400 res. Then afterwards with my 1440p monitors I've done 5K (5120 x 2880 with 4x scale factor) and 4K...