i've just bought a SAMSUNG S27A850D monitor, capable of 2560x1440 resolution
i attached the HDMI output from my Acer 5742g notebook using an adaptor
unfortunately the computer has an Optimus NVIDIA GT540M, and i use Bumblebee
the monitor is recognised and the EDID read, but the maximum resolution in the settings is 1920x1200
adding a New Mode with xrandr i can get the full resolution:
unfortunately the display is badly pixelated and looks like the RGB subpixeling goes wrong (see the attached picture)
xrandr --newmode "2560x1440_60.00" 241.50 2560 2608 2640 2720 1440 1443 1448 1481 +hsync -vsync
xrandr --addmode HDMI-0 "2560x1440_60.00"
xrandr --ouput HDMI-0 --mode "2560x1440_60.00"
the fonts are very small, smaller than the change in resolution can justify
do you have an idea of what can go wrong?