DriverHeaven has compared the architecture of ATI's R520 with NVIDIA's G70:
Last week we looked at the performance of ATI’s Radeon X1800XT videocard when at stock settings and compared it to numerous other videocard configurations including the GeForce 7800GTX. On the whole the XT was ahead of the GTX in performance when using DirectX based titles. When using OpenGL the performance leader was the GTX. What we also looked at in that article was the new GPU design that ATI were using and made comment on how it differs from other architectures.
Over the past week we’ve seen some comments from people interested in just how good the G70 would be compared to the R520 if both had the same number of pipelines and clockspeeds. So off we went to see if it was possible to get the required configuration up and running.