IT TURNS out that R423 based X800GT cards will come very close in overclocking to R480 chip based X800GTs. It's kind of surprising but you cannot expect magnificent scores from R480 based cards as the original chip is just a bit faster than the R423.
We also learned that both chips are actually priced very similarly so it turns out that most of the manufacturers can afford them and get them of their X800GT cards.
But there is a catch. R480 consumes a few watts more power and can possibly run just a little bit hotter than the R423, but I don’t think that you will be able to tell whether you are buying the R423 or R480 based card.
The only way to tell would be to open the box, take the cooler off and look under the hood. Most shops will forbid you from doing that and when you buy it it's usually too late. The key message could be that you should not make a big deal when you get a R423 based card as it will perform and overclock very close to the R480 based X800GT. Oh yes, ATI likes to mess with your brains, it just can't help it and I believe that most of the time even the in house people are confused with all those chips and names. µ
izvor:
http://www.theinquirer.net/?article=25658