Im looking to buy a new laptop, one of them is 750 dollars and the other is 820, the one for 750 dollars has gtx 670 and a 17 inch screen" and the one for 820 dollars has a gtx 680 and a 15 inch screen, is the extra 70 dollars worth it for the gtx 680, and they are both msi laptops, but i dont know the model numbers.