Things have been heating up with the late introduction of X1K graphics cards from ATi. NV4X R42X ASICs were going head to head for the most part. In some benchmarks however 6800 Ultra took the crown from X850 XT and vice versa. The most discussed and apparent reasons for R520 being late were production problems. The majority of chips did not pass high clockrate tests. Failures in sillicon were random and not known for a long period of time. Once the problem was narrowed down to 3rd party IPs crippled design, GPUs started to yield proper clockrates. This goes to show you how a small flaw can contribute to massive delays.