Using triplehead2go with ATEM 1 M/E
So you set the resolution of your TH2G to 720p50? In that case you don't get 720p on every output but 1/3 of that vertically. You have to set your th2g to 3840x720 so you get three 720p signals on your outputs.

I also recommend using the Matrox App for setting resolution modes instead of the windows/osx display manager.