The trick is that the X1800 XL cards, currently available on the market, were initially planned as X1800 XT or X1800 PRO, that is products with higher frequencies than 500/500 (1000) MHz. But the problem with unstable performance of the cores at above 550 MHz forced the company to change its plans. So the first lucky buyers of X1800 XL can enjoy wonderful memory overclocking up to 1400 MHz.



Link: Digit Life