Their horrible yields. Not just with Fermi but also when Cypress first launched, ATI had the same problem. I use ATI in my system, but I'd still like to see a non crippled Fermi card.
i think that they are doing fine right now. even if the yield is high i still believe that we are going to see cripple chip because i don't think they will simply throw out those bad chips. if they do then they are not going to make much profit. that's why we always see 'green' edition card
The cripled chip is because nVidia made a new mod on fermi, it always takes a little while to get it right with a new design even if its just a slight modification on the old one.
At least in the Nvidia case, it's not TSMC's fault that Nvidia wanted an insanely large die for Fermi. Isn't it nearly twice the size of similar ATI chips?