Hi Sven, Thanks a lot for the advice!
I added Stretch main, contrib, and non-free to my sources.list, and upgraded my kernel and packages to their latest versions. I'm now running kernel 4.6. I also installed firmware-linux-nonfree again.
I created a file at /etc/udev/rules.d/10-local.rules with the following line in it. ACTION=="add", KERNEL=="0000:01:00.0", SUBSYSTEM=="pci", RUN+="/bin/sh -c 'echo 1 > /sys/bus/pci/devices/0000:01:00.0/remove'"
Now, I'm able to use the Radeon HD 8650M (the low-powered graphics chip) in my MSI GX70 laptop!
I can't seem to make the Radeon HD 8970M chip work by modifying the above 10-local.rules file to disable the 8650M chip at boot. But for the moment I'm just happy to have some hardware acceleration, so that I can watch movies and edit images without stutter.
I hope this helps anyone else who's got a similar setup, because this has been a real pain for me!
Thanks again! - Justin Belanger
