PC Perspective posted a review on the Sapphire Radeon HD 4850 X2 video card

Why would just one board partner be willing to offer such a compelling part? There several factors that likely include the economic slump, the slight drop in prices on the HD 4870 X2 cards and inventory availability. Even taking that into consideration I find it very confusing that AMD seems content to have this graphics card be such a low volume product. With its great price (currently competing with NVIDIA's GTX 280 cards) and performance advantages (that you will see in our benchmarks) I really think the Radeon HD 4850 X2 could catch on in the enthusiast segment.

Sapphire Radeon HD 4850 X2 2GB Review - GTX 280 killer