I realize that given the apparent hardware-level issues I'm having, my troubles may have more to do with the kernel than with NVIDIA's drivers. I would really appreciate any pointers anyone might have on how to proceed.
On linux 2.6.32-71.29.1.el6.x86_64 (Centos 6.0) I get this in the logs
# modprobe nvidia
Sep 19 10:28:19 isis kernel: nvidia 0000:07:00.0: PCI INT A -> GSI 30 (level, low) -> IRQ 30
Sep 19 10:28:19 isis kernel: vgaarb: device changed decodes: PCI:0000:07:00.0,olddecodes=none,decodes=none:owns=io+mem
Sep 19 10:28:19 isis kernel: NVRM: loading NVIDIA UNIX x86_64 Kernel Module 280.13 Wed Jul 27 16:53:56 PDT 2011
One thing I noticed that I seem to be missing this line (found by googling for keywords):
[ 11.874730] nvidia 0000:01:00.0: setting latency timer to 64
I'm drawing a blank here, please point me in a direction if you can see one!