ATI's R580 is X1900XTX
 

ATI'S LATEST greatest chip finally got the name. we can now confirm that the one that we know as R580 is going to be know as X1900XTX. We don’t have the slightest idea why ATI added an additional X to the name.

Unlike our Chinese friends from HKEPC reported the X1900XTX will be clocked at 650 MHz core and 1550 MHz memory. It will end up very close to the original R520 clock speeds.

http://www.theinquirer.net/?article=28690