That is a very decent CPU (even a 980ti will not make it be a noticeable bottle neck.), so it is clearly a graphics shortage. what do you want to play and at what frame rates? what resolution? With out knowing any of that I will say that the best you can get for that range is either an R9 290X or R9 390 or a GTX 970. if you only want to play at 1080p, which is a good idea in terms of price, I would get an R9 280X or and R9 380X or a GTX 960.