What is the school of thought involving 2 different GPU's? For example I have the MSI GTX 770 Twin Frozr Gaming edition. I'm thinking about putting the GTX 660 TI. Will it make a difference? Will it improve the way I view video games. I know my M/B has to PCIE3.0's, so I'll be able to attach it. I would like to make an informed decision. So thanks in advance.