masbo,

Voltage scalling as on HD5870, GPU is a true bottleneck, I gained 250pts going from 4.95 to 5.1GHz but gained 700 pts for each 50MHz GPU bump. Memory isn't as critical due to 256-bit bus. No coldboot/coldbug until ~ -170°C (tried a bit with LN2 too but didn't push it as insulation wasn't ready to hold it), just like HD5870 I have tested some time ago: http://www.oc-lab.si/forum/viewtopic.php?p=75742#p75742

Best Regards,
Niko