Hello, I have an Intel Core 2 Duo E6600 at 2.4GHz stock and it has been an awesome processor and I am still not sure if the Intel Core 2 Quad Q9650 would even give me any boost, it is really fast and I want to also get the GIGABYTE GTX 770 Video Card if I do go down that path, I can run Battlefield 3 and Far Cry 2 just fine. But I want to get Battlefield 4 and Call of Duty Ghosts soon. My current Video Card is the GIGABYTE GTX 650 Ti.
The Q9650 will be much faster. But it still will probably bottleneck the GTX 770. GTX 760 not as much. But the Core 2 series is at the end of its modern gaming life and your better off keeping your current system and overclocking it until you have enough for a new build.
The Q9650 will still be able to play modern games from low to high settings for easily the next 3 years IMO. When 2018 rolls around i'd still say that you'd be able to play most modern games at low settings. The reason for this is that games are going to become more and more GPU intensive while CPUs tend to have it easier. We're in the age of quad core gaming.