Even though this card already runs extremely hot, FUD Zilla claims the ATI Radeon HD 2900 XT still has some overclocking headroom. They say the card overclocks from 745MHz to 840MHz without much trouble.
The card at its default 745 MHz and 1656 MHz memory scores 10,650 in 3DMark06.
The overclocked one will gain some 600 points and the card was stable. It didn’t want to go any higher than 840 MHz, but maybe some other cards will. Stable at 11260 points doesn't looks bad at all and we are sure that you would get some performance boost in games.