German website 3DCenter.org figured it was a good idea to leak internal information from an AMD reviewers guide, in this case a comparison inbetween the Radeon HD 7970 and GeForce GTX 580 appeared.
The first picture below is a screenshot of a graph in which the two GPUs are compared along a variety of tests, at a resolution of 2560 x 1600. Worth noting, reviewer guide performance numbers are always exaggerated a little and shown in a way to benefit the manufacturer, in this case AMD/ATI the best. Only real world performance numbers measured by objective reviewers count.
And for that you'll need to wait another day or two for the real proper reviews and numbers ;)
