Catalyst 11.6 in Linux allows you to bypass the BIOS limits now. 11.5 didn't.
Adapter 0 - ATI Radeon HD 5800 Series
Core (MHz) Memory (MHz)
Current Clocks : 975 300
Current Peak : 975 300
Configurable Peak Range : [600-875] [900-1200]
GPU load : 99%
I've tested it on both Sapphire and Gigabyte 5830 cards.
Cheers,
Kermee
... Goes to download Catalyst 11.6 ...