Not really. You could hook up the 2nd monitor into the 2nd card to free up a few megs of vRAM on your main GPU. But on the other hand, this increases the load on the PCI-E bus and the cpu, so it's not really worth it. If I remember right, GTX680 supports up to 4 monitor outputs simultaneously, so if you are going for more than 4 screens (like me), then you will need the 2nd card, otherwise, i'd say keep it in it's box.
9/11/14 at 9:17pm