having vsync enabled only fixes tearing issues for a single screen, i think fingers is try to synchronize multiple screens. i have no experience with this so i wouldn't know how to do that but i think quadros support mosaic to get this done, not sure if it works with resolume though so maybe someone else can comment on this
The way I've done it is with a single DP output to an ImagePro or Novastar at the highest res it will take. The IP or Nova then is what sends to the screens and syncs. If you need multiple of those then you need quadro cards with quardro sync cards.
Quadro cards have the extra ability to sync all output ports to a single clock (it's more complex than that but think of it working in the same a fx4 works). Geforce cards do not have this ability. I've done a show with 8 media servers running Quadro cards and was able to get (3) 4k outputs to sync per server using the Quadro cards.
You can then push each 4k output to a fx4 to get (4) 1080p outputs in sync and then connect the fx4's to each other to sync the 3 units that way for a total of (12) 1080p outputs in sync per server if that is needed.