If you edit your post to match this form then we will be able to give advice tailored a lot better to your specific needs.
P.S. I'm guessing, judging by the style of game it will be and seeing as the game hasn't even been released yet, that you will have a rough time cranking settings up to high in a $650 PC build. You have to figure $100 of that goes to your operating system, so your best case scenario puts you in the neighborhood of a $500 build from the quarterly Tom's Hardware System Builders Marathons. I'm guessing (similar to Starcraft 2) that Total War: Rome II will actually lean pretty heavily on CPU usage on a lot of the maps.
You need to follow the proper form, so we can provide the most accurate setup possible. But here I have designed a build that comes in at $563.
The GTX 660 is only $9 more than a GTX 560Ti, but it offers about Twice the VRAM, ~30% more performance, and uses less power.