AMD’s RV790 will probably be remembered as the first GPU that will easily overclock to over 1GHz core clock.

Some partners will ship overclocked cards but 900+ MHz should be the fastest clock out of the box which with some little help of the overdrive tool, you might get the chance to go over the magical 1000MHz barrier. 

With water-cooling, we might be getting over 1000MHz easier, but we are not sure if the high clock should be enough to beat GTX 275. Nvidia’s partners will of course overclock their GTX 275 cards and again give AMD a run for its money.

Nvidia’s 1000MHz+ clock will have to wait for 40nm we reckon.