We would have to analyze failure rates on PC market GPUs to come to a better assumption.
Didn't Nvidia have manufacturing problems with some of the G8X derivatives? Or was it the mobile G8X GPUs that were having major thermal/solder issues in laptops that caused a recall and lawsuits?
Iirc most of those G8X derivatives were 90nm based...I believe there were some 80nm G8Xs (note not the big G80 itself) that despite being lower models they had thermal and solder problems.
g86 and g84 were used for the 8400GS 8500GT, 8600GT, 8600GTS not to mention mobile, so most G8X were 80nm and had the worst reliability I ever experienced with graphics cards, all the 4 8600GTs I owned had random crashes and died a after a few months, I remember buying an HD 3850 and being so relived with finally having a stable card again... it was also a mess with all the laptops failing http://www.tomshardware.com/news/nvidia-g84-g86-chips-overheating,6121.html
I'll never understand how this didn't cause bigger problems for Nvidia...