AMD's anticipated Radeon HD 4850, the follow-up to its 3850 GPU and rival to Nvidia's GeForce GTX 200 series, appears to have made an unscheduled early appearance on Amazon.com courtesy of board seller Diamond Multimedia.

Amazon quickly took the page down, but not before a number of sites scribbled down the details. The basic speeds and feeds are a 625Hz 'RV770' core with the board's GDDR 3 running at over 2GHz.

Pictures of the board show the usual two DVI ports and TV-out connector on the back. It's essentially the mainstream version of the Firestream 9250 workstation-oriented graphics card AMD launched this week. That board contains 1GB of GDDR 3, so it's a good bet the 4850 will too.

The board is a single-slotter, it would appear from the pics. Equally interesting is the reference to the HD 4850's support for "game physics processing". Last week, AMD said it was working with Intel subsidiary Havok, to enhance support for the latter's Havok FX physics-processing-on-GPU technology across its product range.

AMD will undoubtedly be using Havok FX to counter Nvidia's promotion of the PhysX technology it acquired when it bought Ageia. PhysX is a key feature of the GeForce GTX 280 and GTX 260.