PHK: informant sent me a NV sent from the Email, the letter referred to knock down the Cayman is not a problem 580. Cayman Pro XT But the letter did not say the Cayman in the end is Pro or XT, but my guess is GTX 580 faster 480 20~30%. The letter also nominal GTX 580 faster than 480 in the game 20 to 30%. NV Cayman's performance should not reach level of GTX580. Finally NV said Cayman's performance should not reach level of GTX580.
I'd say this is a legit leak.