Created attachment 126259 [details]
working kernel version

Originally diagnosed in https://bbs.archlinux.org/viewtopic.php?id=216364

distro is Arch. Music studio machine with an nvidia GeForce GTX 460 and
"ACHIEVA Shimian QH270-Lite 27" Wide QHD PC Monitor DVI-D 2560x1440" connected
via DVI.

Have been using nouveau without issue since 2012. Kernel update from 4.5.1-1 to
(4.6.4-1 or 4.6.7-rt11-2-rt) causes a lower than standard resolution during
kernel messages then no video once X attempts to start. Reverting to 4.5.1-1
works perfectly. "nomodeset single" kernel options allow me to get to a
terminal.

some package versions that don't change between kernels:
extra/mesa 12.0.2-1 [installed]
extra/xf86-video-nouveau 1.0.12-2 (xorg-drivers xorg) [installed]