I was too convinced that GK104 wasn't meant to be the GTX 680 but when you look at the date on the HPC GK110 then you can see that it was too late to be even shown as a consumer part. I would have been GF100 all over again, infact there is no GK100 and I'm fairly sure the reason are the very poor early 28nm yields. I mean 7.1 billions transistors on a new manufacturing node? Would have costed an arm and a leg to produce in a sizable quantity for their GTX 670/680 lineup. I think that if the 7970 was faster than it is now, like 10-15% more then Nvidia would have launched GK104 as midrange chip and they would have launched the GK110 as GTX 680 when they could have had reasonable yields. Nvidia would have probably been without a single GPU capable of fighting AMD toe to toe and they would have probably used a dual GK104 solution. But meh things have gone differently and we can only speculate.