FurMark is a very intensive OpenGL benchmark that uses fur rendering algorithms to measure the performance of the graphics card. Fur rendering is especially adapted to overheat the GPU and that’s why FurMark is also a perfect stability and stress test tool (also called GPU burner) for the graphics card.
The benchmark was rendered in fullscreen mode with no AA enabled on both video cards.
Benchmark Results: FurMark gives us some interesting results. Neither CrossFire nor SLI systems scale, so this benchmark is really only good for looking at the single GPU cards. The ATI Radeon HD 5850 was ~22% slower than the Radeon HD 5870 as seen in this benchmark.