Redhat Linux, Quadro K420, Acer B276HUL x2, Club3D CVS-5400 MTS hub, monitors blank, won't wake up

I am running a new NVIDIA Quadro K420 graphics controller in a Red Hat Linux machine, coupled to a Club3D CSV-5400 MST Hub, currently driving two (2) Acer B276HUL monitors.

Here are the relevant system details:

uname -a
Linux atlas.as.utexas.edu 2.6.32-220.el6.x86_64 #1 SMP Wed Nov 9 08:03:13 EST 2011 x86_64 x86_64 x86_64 GNU/Linux

I am running the current NVIDIA driver, 361.42, and NV-Control, 1.29.

The two monitors are interfaced via DisplayPort 1.2 compatible cables, 2m long, and running in their default configuration at 2560 x 1440 x 60Hz.

From a cold boot, the system will run though POST as usual, boot, and start successfully executes, with the Gnome display as expected, and login prompt. Things behave, the monitors will go to sleep and reawaken on keyboard/mouse input, however logging out of the Gnome/X session causes both monitors to blank, and they will not see any signal from the DisplayPort/Club3D MTS hub. I can ssh into the machine, but any, and all attempts to restart the X session fail, and the monitors never leave their blanked state.

Only a cold reboot will restore operation.

I have done significant trouble-shooting, and find that removing the Club3D MST hub from the system in part remedies this problem, I can log in/out of the Gnome/X session without the single monitor blanking. Unfortunately, this is not a useful configuration, and in the longer term, we are planning on adding two more monitors…

I’ve run nvidia-bug-report.sh, and can provide the gzipped log…