Just throwing this out there, even a single 670 is a MUCH smarter option than a 680.
A 680 is about 5% faster than a 670. (2-3% after overclocking both cards.)
At the same time, it's 25-30% more expensive.
That's just a bad purchase, especially when you consider that both cards will max out basically any game out there, why would you waste the extra $100-150?