Eh? What would the 670ti be, why would it look as good as a 680gtx but be much cheaper exactly?
Though you have a point, Nvidia might not be able to make very many cards that do 1056Mhz, it might be the equivalent of a 7980 with 1200Mhz at stock, heavily binned, very few, priced through the roof to prevent people wanting to buy it and a lower TDP, lower clocked card for significantly cheaper available in higher quantities, and a lower card again with bits disabled.
It is looking for all the world that the 680gtx is just a heavily preoverclocked part, vs a 7970 which is a stupidly underclocked part, and I still say a 7970 overclocked to a safe but high level(1150-1200Mhz) with a higher TDP will easily beat a 680gtx which will likely have little to no overclocking headroom.
AMD are being utterly stupid though, just for the love of god release a 7890 with 30% higher clocks while dropping the price on the 7950/7970 a bit BEFORE Nvidia launch and make them look completely stupid, releasing a high end part they've claimed beats AMD easily... after.... more expensive.... slower.... same TDP or even higher.
One of those is suggesting that a 670gtx uses around the 7970 type average gaming power, while a 680gtx uses 230W, which is basically exactly where a 1200Mhz 7970 would be, which would likely blow GK104 away with that clock speed.