The current X1900GT uses a cut down version of the R580 chip, which makes it quite expensive to produce. ATI is planning to replace that chip with a RV570XT. The cards are codenamed Hellfire 1 and Hellfire 2 and will run at 600 or 650MHz core, depending on the SKU, while the memory will run at 1100MHz. The Hellfire 2 uses GDDR 3 memory with a 256-bit memory interface and its memory runs faster than on Hellfire 1. Hellfire 2, Radeon X1900GT at 650MHz core and 1100MHz memory is the replacement for Radeon X1900XT that is supposed to phase out slowly. Hellfire 1 has eight layers PCB and also uses 600 to 650MHz core clock but its memory works at 800MHz and it will probably target the more mainstream market. Both cards are PCIe and support two Dual DVI ports and AVIVO marchitecture. Expect them to be available in October of this year.
http://www.theinquirer.net/default.aspx?article=32807
