This is following up from a issue I originally emailed to NVIDIA regarding the 340.24 drivers on a dual-K600, four monitor system. I have been able to relatively isolate the issue - using a fresh install of Debian Jessie (testing) and the packages of 340.24 included in it, you basically just have to log into GNOME and start doing something - anything. The display except for input freezes, then input freezes too, then you can’t do anything until a few minutes pass (presumably screensaver timeout) and the monitors one-by-one flicker and turn off, then your whole X session is forcefully exited with lots of messages to dmesg and you’re returned to the login screen.
I’ve uploaded a PDF with repro instructions - I actually did the install using the debootstrap approach since I wanted to still use this machine while it was installing, but I’ve highlighted what the equivalent USB install would do, then the common parts of the reproduction.
I’ve also uploaded an nvidia-bug-report log from the exact scenario I describe near the end.
[EDIT: swapped out dropbox link for attachments.]
fresh-install-1.log.gz (57 KB)