Radeon HD 2900 XTX pushed to Q3
R600XTX, the 1024 MB GDDR 4 card, has been pushed to the next quarter. This is just one in a series of ATI's failures, but of course DAAMIT will call this a strategic decision. R600XTX won't see the face of retail / etail stores till Q3 2007.

We know that something went wrong with the samples and that the there were some severe performance problems with the latest batch of GDDR 4 cards. Basically 512 MB DDR3 version with 1600 MHz memory was beating the GDDR4 version with 1024 MB of GDDR 4 memory clocked at 2200 MHz.
http://www.fudzilla.com/index.php?op...d=661&Itemid=1