https://bugs.freedesktop.org/show_bug.cgi?id=51798

--- Comment #3 from Ilia Mirkin imirkin@alum.mit.edu ---

ls /sys/bus/pci/devices/*/drm/*/card*/enabled | xargs -I {} -i bash -c "echo -n {}: ; cat {}"

Here's a neat trick:

grep . /sys/bus/pci/devices/*/drm/*/card*/enabled

I think "enabled" is like "is there a KMS user that has enabled this connector" (probably something to do with assigned crtc's or who knows). e.g. Xorg. Looking at your xorg log, it only loads for the first gpu. Do you have an xorg.conf that hardcodes the busid?

In any case, I'd highly recommend retesting with a new kernel and xf86-video-nouveau (and maybe xorg-server).