I am running an alienware 18X R2 with the following specs:

intel i7-3840QM, Windows 7 Pro

32Gb RAM

Dual GTX 680M's.

While I don't think it would be worth it to upgrade the processor, and only minimal gains could be achieved from the RAM, could my system be upgraded to either 1 or 2 GTX 980M's. If so, what other concerns would there be, i.e. heat dissipation differences, that I would have to account for for this upgrade?