tbh I suspect they just didn't have the yields to do it, and I doubt they could push a fix any quicker than they have. Doesn't feel like that long since the first working silicon for GK110 was coming out (hmmm, checking back official release for Tesla K20 was November last year, so 8 months ago - Titan didn't land until this Feb though). Given the increase in working silicon and reduced tdp this looks like a respin or different stepping, potentially (although we don't know the clock speeds, so it could just be lower clocked to keep TDP in check). I wouldn't think 6 - 8 months was an unreasonable time for that kind of turn around...