crookedvulture writes "AMD's recently introduced Radeon R9 290X is one of the fastest graphics cards around. However, the cards sent to reviewers differ somewhat from the retail units available for purchase. The press samples run at higher clock speeds and deliver better performance as a result. There's some variance in clock speeds between different press and retail cards, too. Part of the problem appears to be AMD's PowerTune mechanism, which dynamically adjusts GPU frequencies in response to temperature and power limits. AMD doesn't guarantee a base clock speed, saying only that the 290X runs at 'up to 1GHz.' Real-world clock speeds are a fair bit lower than that, and the retail cards suffer more than the press samples. Cooling seems to be a contributing factor. AMD issued a driver update that raises fan speeds, and that helps the performance of some retail cards. Retail units remain slower than the cards seeded to the press, though. Flashing retail cards with the press firmware raises clock speeds slightly, but it doesn't entirely close the gap, either. AMD hasn't explained why the retail cards are slower than expected, and it's possible the company cherry-picked the samples sent to the press. At the very least, it's clear that the 290X exhibits more card-to-card variance than we're used to seeing in a PC graphics product."