A GDDR 4 version of R600 should end up clocked at 2100 MHz. The first R600 version comes with 1600 MHz GDDR3 while the second, more expensive GDDR 4 2100 MHz card will follow. Both cards will end up clocked at around 800 MHz for the core.
GDDR 4 card is will go in production on the first days of May. The samples should be ready as we speak but not in volumes of course. End users should get this card in middle of May.
The card's product number is 102-B007 and it comes with dual DVI and Vivo, HDMI and HDTV support. GDDR4 R600 is a 9.5 inch card and should have the same cooler but more bandwidth.
Unfortunately there won't be a big performance difference between this one a GDDR3 version. ATI still didn’t change its mind, this card still has lower priority. R600 with GDDR3 will be first.