Hi Tech Legion has posted a review on the Sapphire Radeon HD 5870 and 5850 DirectX 11 Graphics Cards
>> Sapphire Radeon HD 5870 and 5850 DirectX 11 Graphics Card Evaluation
ATI is the first video card manufacturer to produce a DirectX 11 capable GPU and have named these the 5000 Series. At this time there are four discreet Direct X video cards available, the 5750 and 5770 which are mainstream and the 5850 and 5870 which are gamer (enthusiast) cards. Sapphire Technologies a manufacturer of ATI Radeon Graphics video cards has released their first round of 5000 series video cards and they are available to the public. The Sapphire Radeon HD 5870, HD 5850 and HD 5770 are all DirectX 11 capable and will be the three cards I will be evaluating. The Sapphire HD 5850 and 5870 which are high end mainstream and enthusiast level cards and the HD 5770 which is a mainstream card all offer the ability to empower your visual computing experience via DirectCompute.
>> Sapphire Radeon HD 5870 and 5850 DirectX 11 Graphics Card Evaluation