I was about to say the same thing about gears.
I see now that I have not mentioned another issue when using discrete card:
If I play a video in browser or with a media player and go to full screen I can
clearly see some image corruption bellow or over the main diagonal (imagine
picture being made of two triangles). The problem is more severe as more pixels
need to be rendered, on still portions of video the corruption is not as
visible.

I assume not many people can dedicate their time to solving this so I will keep
posting here as new kernel and driver packages versions get uploaded to debian
repos.