Bug report output from 450 (working fine) and 460 (exhibiting the problem) are attached. The files are both taken after booting, starting X, then switching the monitor to a new input, and then shortly after switching back.
For reference, the original bug report with Debian is at https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=981114
nvidia-bug-report-450.log.gz (103.8 KB) nvidia-bug-report-460.log.gz (67.7 KB)