Uninstalled drivers. Unfortunately Guru3D's driver cleaner is no longer available. Rebooted system and search for any remnants of nvidia drivers (didn't find any). Rebooted one more time for good measure.
Install 266.58, and booted ArmAII OA. Still getting the same problems.
I started from the top of the 3D properties in the Nvidia Control panel and changed one thing at a time. If changing a setting had no discernible affect I restored the settings to default.
Finally got to the Multi-GPU Rendering Mode. I assume this is SLI. I set it to Single GPU and everything worked fine. Was kinda surprised how smoothly it was running so I ran EVGA's Precision to verify only one core was being used, and it was.
So, I remember reading somewhere about a hack or trick to get SLI working. If I recall it had to do with a previous version of the game. Anyone have an idea to get both of my GPU's back in the game?