I have a GTX 670 vanilla version. In the NVIDIA control panel do you guys set it to Let the 3D application decide or Use the advanced 3D settings? I used to keep it on Use the advanced 3D settings with minor changes to the global settings. I would put it to single display mode and everything else default, but then I realized that if I'm barely making any changes then why not just leave it on Let the 3D application decide? 
 
So my question is should I just leave it on let the 3d application decide if i'm not making a bunch of custom profiles for individual games and barely adjusting the global settings? I'm not noticing any difference.

I usually leave it on global settings unless I want to change something for a specific game. I don't know if that helps you but I haven't noticed much of a difference either way, that's just my personal preference.

Just a quick question while I try and figure out the SLI options I havent used in a couple of years. I dont see an option to select a SLI rendering option in my nvidia control panel/manage 3d settings tab. Everything else looks correct as far the settings.  It is running in SLI now with the new 680. GPU's usage is running equal and all clocks and stuff are kicking up when in a game equally. I even tried enabling the SLI green indicator and dont see it in the game (pCars actually), but that might be due to some injectors I'm running for the game in DX11.
Im nearly 100% positvie I reinstalled the drivers correctly. Uninstalled Precisionx, deleted the 310.90's reboot, reinstalled the310.90's, reboot, checked everything, reinstalled precisionx, rebooted, checked everything yada yada yada.