As I understood, they carried me to a separate topic, therefore I will add. I understand that much will take care of the quality of the splitter, here are 2 variants that I want FosPower FOSAV-2157 or Zettaguard ZW-140. So, the first has many ports and HDСP support, the second has many video support formats (URL moderated.) Based on these variants, the question remains the same)
It depends on your application. Are all 3 of your sources going to be next to each other to form one giant canvas? If so I would recommend using a FX4.
If the outputs will be away from each other and sync isn't an issue, then it really doesn't matter. The issue you will run into is screen tearing if your outputs are not a Quadro series card.
You will want to make sure your UI is on a monitor connected to your high performance GPU (such as Nvidia or AMD) and make sure this GPU is configured to do the rendering.