I have Lenovo Y40-90 laptop, and have Ubuntu 14.04 with integrated Intel graphics card and AMD Raden R9 M275 graphics card. I have also installed AMD Catalyst Center to switch between Intel and Radeon. I followed this answer: How set my monitor resolution? to set the resolution to 1600x900 (which was not in the original list of the resolutions).
I am able to set the resolution everytime, but after every reboot, or while playing a game (DOTA2, here), the screen flickers and it goes back to the highest 1920x1080. Also, I get a very tall error dialog box which is this:
I shall be really grateful if somebody could help me in setting the 1600x900 resolution permanently.