TSMC 40nm process is in bad shape
 

The guinea pig customer and chip, RV740 40nm are not exactly flying out of TSMC's manufacturing lines as we've learned that 40nm was a slow and bad transition for TSMC. As you could imagine by know, RV740 and Radeon 4770 are not available in hundreds of thousands and due to its great performance it gets solld out quicky, but the part of the reason is that yields are bad and ATI can not produce as much as market wants.

TSMC is the one to blame as their 40nm process has a lot of leakage and bad yieds. The company is working on many Nvidia’s mobile and desktop chips as well as on ATI’s new desktop chips, all 40nm and we can only hope that yields will get better.

http://www.fudzilla.com/content/view/13855/34/