Bit-Tech published a review of Sapphire's ATI Radeon HD 4850 X2 2GB graphics card

Despite these flaws, the Sapphire Radeon HD 4850 X2 does deliver a generally better gaming experience than Nvidia’s more expensive GeForce GTX 285. The cheapest we have been able to find the 285 for is around ?300, including VAT, which makes it ?40 more expensive than the 4850 X2. That makes the decision difficult and while we’d typically recommend a single GPU solution almost every time (especially in light of what we’ve described above), the price difference makes it an awkward choice – the GTX 285 is 15 percent more expensive and it’s slower in four of the seven games we’ve tested here.

Frankly, the Sapphire Radeon HD 4850 X2 is too loud for a modern gaming system, driver support isn’t where we’d like it and the GeForce GTX 285 is too expensive. In light of this, we don’t believe there is a perfect choice in this segment of the market and it opens up a window of opportunity for the manufacturer who wants it the most. Right now, we’d avoid this part of the market altogether and either go higher or lower depending on your screen size and budget elasticity.

Sapphire's ATI Radeon HD 4850 X2 2GB graphics card Review