I've found some posts via Google saying they were able to do it. However everything pointing to how is usually a dead link or outdated information.
 
I have a center monitor with 2560x1080 resolution, and two side monitors at 1920x1080. How can I get past the "you can't do it" shenanigans and actually enjoy Nvidia Surround?
 
I attached a picture of my setup. Would be nice to turn my side monitors to landscape and enjoy some old games again!
 
I appreciate your help!

Hello,
 
I have been able to run 3 monitors in surround with different resolutions, however it can vary from driver to driver and is a bit odd to play with in general.

I think the main issue at the moment will be all the monitors have to be either vertical and or horizontal, not the mix match that you have. Are you trying to game 3x1 and or game off 1x monitors?

you will want to have 3x monitors connected, leave the 4th monitor disconnected. Attempt to setup surround, after it is setup, connect the 4th monitor, open up the nvidia control panel, go to set up multi monitors, enable the 4th and most of the time you are golden from there.

To help verify where the issue may be, will be not to use the 21:9 ratio monitor (sometimes these will be label as 2 in 1 screens), try the two sides and the top monitor and or try the 21:9 monitor with another monitor in surround, not really have worked with many 21:9 I can not guarantee at this point, we can achieve what you want.