It's good, but get a 7970. It is as strong as the 680, and it can destroy it in overclocking. Or you could just get a 7970ghz which is flat out as strong as a 590. You probably don't need watercooling even if overclocking, but it will still be way quieter. The get 2x4gb ram.
This is my first computer build, and there are so many brands of 7970's which should i buy.