Because Low K is more expensive NVIDIA's chip actually ends up cheaper than ATI theirs.
Our ATI knowledgeable source said that could be possible if it used more layer on chips or even if it used a 110 nanometre process. Nvidia was clear in the past that it is using 130 nanometres, but in this industry you never know.Source: The Inq
From logic it means that 60 millions of transistors means a significantly larger die but it is all about packaging I guess.