Is there a way to configure and run all three GPUs simultaneously while using a computer?
Does anyone have such configuration?
I think you need more details of what you consider «running». Using displays connected to all three (under which graphical system?), using automatic rendering offload, using them for GPGPU computing…
I have never had a system like that; but from general experience with the parts involved I would expect things to work fine without special effort with tools that let you choose explicitly which GPU to use for rendering/computation. Anything else risks being dependent on what exactly you are trying to do.