Loki wasnt recognizing two of my montiors. I managed to fix that through installing the NVIDIA Driver for my card, but now those two monitors dont have a correct resolution and i cant set it up to be higher as 768p. Those two also get displayed as "Unknown display" in my System Settings -> Displays. They show up as DFP-0 and DFP-4 in nvidia-settings but my working one is showing up properly.
You might want to use xrandr to define the monitor resolution. That's what I did for my second monitor (using an Intel card and not Nvidia).
I had the same problem when using driver nvidia-304 after I installed the driver nvidia-361 the problem solved