It is possible to get an AMD Firepro and Nvidia Geforce cards (shown above is the W8100, a Geforce 780Ti, and a Geforce 780) to work together on Pro apps, where the Firepro does the heavy lifting on the UI, OpenGL and Open CL, for example in MARI.
The Geforce's don't drive screens and are used for CUDA accelerated applications such as Octane Render.
So to begin with the NVIDIA cards were already installed, so I needed to remove the current Nvidia drivers using a free application called Display Driver Uninstaller to strip out the Nvidia drivers, one reboot into Safe mode later, the PC is clean to accept the new drivers.
I removed all the Nvidia cards, and then installed the Firepro, booted up, and installed the AMD drivers onto the C: Drive as it would be the main UI card.
I then installed the Geforce 780Ti, and downloaded and reinstalled the Nvidia drivers onto ANOTHER DRIVE (or a partition should do). This worked fantastically well - all of the pro apps could use CUDA, the only thing that seems to be a bit off is the Octane Render plugin for C4D render countdown is a bit hit and miss, but otherwise all is good.
This means that hopefully I get the best of both worlds, the power and stability of a workstation card for my day to day UI needs (along with really strong OpenCL performance), combined with CUDA grunt as and when required.
If you have any questions or have a similar setup, leave a comment below.