The yield rumours are from last year on semi-accurate and given the size of the chip should come as no surprise. As for the underclocking of the GPU, this post on Gaf has one theory:
http://www.neogaf.com/forum/showpost.php?p=61372981&postcount=1084
Don't know enough about chip development to know if this is true but it'll be interesting to find out if it's true or not.








