Hardware Canucks posted a review of the Sapphire Radeon HD4850 512MB graphics card.

The HD4850 is a product which is aimed straight for the throat of Nvidia's 9800GTX and has actually incited a quick and dramatic response from the boys in green. After the initial performance reports of this card were released, Nvidia quickly knocked nearly $100 off the MSRP of their then $300 GTX so it could compete mono a mono with ATI's new wunderkind. Not only is the HD4850 seemingly perfectly suited for budget-minded gamers in the $200 price bracket, but it also offers a bevy of other features including audio out through HDMI as well as Havok physics support. The more features the better we say.

Sapphire Radeon HD4850 512MB Graphics Card Review