I have a notebook with two graphical cards. The integrated one is slow, but consume less power and better for most time. But it's impossible to play any games with it. I am using nvidia-xrun which runs desktop environment using the second graphical card. Also i've tried to use Bumblebee with VirtualGL or with Primus, but they have very poor performance. So, what about to integrate something like nvidia-xrun into Steam and use it on notebooks with two graphical cards.