I am going to assume you have innerspace. When you create a setup for a client you can choose a display for them. The options are primary, secondary, tertiary and a 4th one (I don't remember what it is called). Set your main as primary and the others as secondary.
Here is the quote I got from Lax ->
The GPU is selected per Game Profile in the IS configuration (right click on IS, select Cofniguration, and it's in the Game Configuration tab). By default it is Application Defined (application being the game, i.e. WoW)
So, what you would do is create additional Game Profiles depending on the number of GPUs (one easy way of doing so is with Add Game, then just modify the new profile through the configuration window).
Assuming you're using ISBoxer, you would then update your Characters in the ISBoxer interface to use the appropriate Game Profile
I hope this helps.
Drommon
Connect With Us