R520's commercial availability was scheduled for introduction roughly one year after R420, i.e. late spring to summer 2005. Initially R520 was on target for this type of timescale, and just three days after the release of the Radeon X850 series, based on R480, the refresh to R420/R423, ATI received their first packaged R520 chips, ready for the bring-up process. Things appeared to be going as planned, with sightings of the product in operation at E3; however, following on from that nothing appeared, even with NVIDIA's release of their next generation G70 product ATI didn't announce any products. Soon stories of leaking issues appeared and eventually Dave Orton, ATI's CEO, announced that the scheduled release had indeed been pushed back due to "a variety of design issues"..



Link: Beyond3d