U can use whatever resolution monitor beside eachother.

But when you game on both togheter with the game on both screens it will lower in resolution to the lowest resolution of the two.

If u use 1 monitor for the game and another for ts/procon or whatever you please it doesn't matter.
You can play bf3 on 1080p monitor and use the lower resolution monitor for ts/procon and so on. :wink: