When we ran the TSMC yield story, we were left owing you an explanation. Time to clear that up too… why does TSMC has "f***** up" yields? Because the chip "some say it doesn't exist" has disastrous yields. We refuse to be drawn into the speculation about whether the GT300 exists or not, since we have enough data that would send nVidia Legal our way - but that was in the past, green guys learned better ;-)
According to our sources close to the [silicon] heart of the matter, the problem that nVidia has are yields in the 20 percentage range. You've guessed, that is waaay [insert several "a"] too low for launching volume production. Even when TSMC improves the leakage issues [the company claims that the leakage issues are now the thing of the past], nVidia will probably send a new revision of silicon - the yields have to be get high enough to earn a little bit of money.
The current situation is that three faulty chips in order to yeild one working one is much too much, since those faulty chips aren't exactly "GTX 360" or "slower Quadro FX" grade material. Some faulty parts might work under forced cooling, but the high leakage is an issue with the current graphics card layout. We won't go into the whole instability, does not work etc situation. As we all know, the graphics chips are at the worst possible position, facing down [unless you put them in testbed/desktop case]. With high leakage parts, the thermal shockwave is sent through the organic packaging to the PCB [Printed Circuit Board] and can cause extensive failure, like nVidia learned with their $200 million mistake called "bad bumps" or simply "bumpgate".
We have the exact number, but in order to protect the parties involved, we are going to refrain from posting the exact yield figure on first batch of chips. All we can say is - not yet ready for production.
nVidia GT300 - GeForce GTX 380 yields are sub-30% - Bright Side Of News*