I'm thinking about buying it, will I be able to play modern games with it?
Your question is a strange one because the GTX 680 is the best card you can buy. The question is not whether it is any good, but whether you really need anything this powerful. True, there is a card called the 690 which is even more powerful, but it is not a viable option for most people.
Your 8GB Ram and i7 2600 are plenty