Nothing wrong with the CX series, but why not go with the AX series, since you have a beast of a videocard?
Or better yet, get something in between the high priced AX and the budget CX. The Capstone 550M is a solid choice (Super Flower made unit). The XFX XTR units just came out on Newegg as well. 550W, Gold rated, Fully Modular, and Seasonic made for under $100.