5870 has a theoretical peak of 2.7 tflops, a GTX680 has a theoretical peak of 3.1 tflops. even a 7970 has a peak of 3.8 tflops. you can argue (successfully) th

5870 has a theoretical peak of 2.7 tflops, a GTX680 has a theoretical peak of 3.1 tflops. even a 7970 has a peak of 3.8 tflops. you can argue (successfully) that it's much easier to achieve a high proportion of peak on GCN cards, but CL code tuned for a 5870s isn't going to be exactly sluggish.