The RSX Chip is based on G70 Chip in turn based on the NV47 (GeForce 7800 GTX) but with only 8 ROPs activated and 128 Bit memory interface. This serie serie of gpu had issues with the substrate, which caused solder balls to break from it. This is the reason of the YLOD. Nvidia produced bad chips in the G70, G79, G80, G86, G84 GPU Series. Just to recall the bad Geforce 8600gt-m in the 2007-2008 Macbook pro's story.