Hello,
 
I currently have a triple monitor set up with an EVGA GeForce GTX 680 Classified. I use it primarily for racing Sims and was wondering if I could add a fourth monitor to this setup? I have read up on this a little but I'm not entirely sure I understand the answers.
In the end I would like one scene to be stretched across all 4 monitors. Unless I'm misunderstanding it, I can only have 3 with the Sim and a 4th that would be independent?
 
Any help would be great!
John

Maybe, you could connect the 4th monitor to a dedicated GPU. You could try with a cheap (but not too old) NVidia GPU for the accessory display. See supported GPUs for your driver.
 
It worked for me in a somewhat different situation, with unsupported 4th monitor.
 
I do it that way in order to get the accessory display to work in a 3D Surround setup (AFAIK, with my GPUs, accessory display is not supported in Surround 3D mode). But I have a weird minor issue : the "accessory" GPU is deactivated after every boot, not shown in NVidia Control panel, but shown as activated in device manager ! I have to deactivate then activate it before NVidia Control Panel can see it, and the 4th monitor turns on. This problem occurs only in Surround mode. Naturally, after every boot, all icons or gadgets located on the accessory display have to be repositioned... Takes 15~30 seconds, but it is worth it...
 
Have a try, it could solve your problem.