LuxMark is an OpenCL benchmark based on LuxRender. LuxRender is a physically based and unbiased rendering engine. Based on state of the art algorithms, LuxRender simulates the flow of light according to physical equations, thus producing realistic images of photographic quality - Gallery.
Info and Download
The default (start-up) benchmark mode is the GPU path.
Here is the my GTX570 (825/2100MHz):