Sapphire Technology, the world’s largest producer of ATI Radeon-based graphics cards, has quietly added an unannounced Radeon HD 2900 XTX graphics card into the list of boards it offers to its clients. Currently ATI, graphics product group of Advanced Micro Devices, only sells “XT” version of the board and emergence of the “XTX” was relatively unexpected.

According to Sapphire’s product matrix, Radeon HD 2900 XTX graphics board will feature 1GB of GDDR4 memory at 2050MHz clock-speed as well as the Radeon HD 2900 XT graphics processor at 740MHz with 320 stream processors. At present, the Radeon HD 2900 XT features 512MB of GDDR3 memory at 1650MHz.

AMD currently positions ATI Radeon HD 2900 XT graphics card as a rival for Nvidia’s GeForce 8800 GTS 640MB and the board’s recommended price is $399. The price of the Radeon HD 2900 XTX remains to be seen, however, 1024MB of GDDR4 memory cost noticeably more compared to 512MB of GDDR3.

Given that ATI Radeon HD 2900 XT already has 105.6GB/s peak memory bandwidth and still cannot beat Nvidia’s GeForce 8800 GTX/Ultra, it is uncertain whether the Radeon HD 2900 XTX will be able to compete against its rivals. Still, with the Radeon HD 2900 XTX its developer will be able to claim the world’s first consumer graphics card with 1GB of memory with the world’s highest peak memory bandwidth of 131.2GB.

AMD and Sapphire officials did not comment on the news-story.