Hello,
I've got three monitors. Two monitors connected to GTX 1080 and the third one connected to integrated graphic card. The game is running on integrated graphic card (intel i7 2600k) and monitor connected to this card. I tried disconnect that monitor but the game didn't run. I tried drag the game's window when I run game in window mode and turn on fullscreen but this caused turn off the game. I tried to force the game to be started by dedicated graphic card in nvidia control panel but it didn't work. (3D Settings/Manage 3D settings/Program Settings/ graphics card rendering OpenGL/ - I've change it from Auto to GeForce GTX 1080). Graphics card drivers are up to date. My system is Windows 10.