Any current top of the range (e.g. 7970) is going to play current AAA titles. You know how these things work.....buy now?.......xfire/sli later?.......wait for next gen?
Your choice.....1st up ---> NVIDIA Titan?
I wouldn't say that the Titan is a recommendable product. It costs $1000, has less performance than even a GTX 660Ti setup at times, and with the 8970 coming around the corner, it's most likely going to have similar if not better performance than the Titan at a substantially lower cost.
IMO get a 7970 now for around $320 since the 8000 series looks like it won't come out until at least September.