I'll assume you are from the United States.
What resolution is the monitor you plan on gaming on?
Yes, 8 GB of ram is enough for purely gaming.
While the GTX 660Ti is a good card, your budget looks like it'll provide for so much more, and I don't even know how to suggest a single card build that will make use of all of that.
Are you opposed to getting an GTX 690 or crossfire (2x) HD 7970s?