ATI's CEO Dave Orton claims the company had problems with the the R520 and the RV530 but now those chips are working perfect.
“To be honest, we’ve had our share of challenges with the R520 and RV530 chips. Even though all the simulations that were done with the chips were looking good, there were still issues with the silicon when it came back from the fab,” said Dave Orton, ATI’s chief executive officer, in an interview with Sonera Plaza web-site.
Orton further said the R520 runs extremely fast, although they are still finalizing clock speeds. More details at X-bit Labs