reading some review article I dug up. I found the Firepro cards work very well with OpenGL, GTX cards work very well with DirectX, and Radeon cards work very well with OpenCL. So it seems like you have situation were, one may want 3 different kinds of video cards depending on the task: a GTX, Firepro, and a Radeon.
three different computers, each dedicated to one of those API’s.
Or one big machine with the three different cards in them. So I don’t know: I am unfamiliar with such a configuration, would the cards fight with each other for dominance? Also most motherboards do not support full 16x on PCIe slots. I’m not sure, maybe someone can tell me, but that would mean one would only be getting full bandwidth on the first card, Unless one gets an expensive $300.00 motherboard that supports, x16/x16/x16.