I wonder if people have considered that perhaps furmark and not their graphics card is faulty?
Take a look at the link below. ATI currently have a "bug" in their drivers that automatically lowers card speeds when the driver detects "furmark.exe". Renaming the executable something different magically fixes the "bug".
Funnily enough this behaviour occurs very early into the lifecycle of the 48xx series which are renowned for running hot and there is an issue with some cards dying due to an inadequately cooled voltage regulator module (brings back memories of certain 7900GT cards).