Wow this game is really broken for Nvidia Surround. I am running 3 x 16:9 monitors. When I deselect Windowed Mode, I get no resolutions to choose from when 16:9 is selected, and the highest resolution when 16:10 is selected is 1680x1050. So basically I can't even run it in one monitor at its 16:9 native resolution, let alone 3. Also I noticed that the arrow keys didn't work in the menu at the broken resolution it tries to run at.I basically have to disable Nvidia Surround and go back to a single monitor for it to work at 1920x1080. Now the arrow keys work also.Edit: Updating to the very latest drivers means I can run a single monitor resolution only on Nvidia Surround. No idea how to make the game run over 3 screens yet. It's not an available option in the resolution drop down. 1920x1080 is the largest I can go.
Edit 2: Haldi showed me how to edit the ini files in Documents\My Games\Fallout4\Fallout4prefs.ini.
On Nvidia, I get some really bad shadowing effects and also the HUD is very stretched and unusable in places.
Good @ 1920x1080:
Not so good @ 6000x1080 (look at the black shadow across the bottom of the white machine in upper left middle)