I just read that the new version of the linux Catalyst drivers, the 1.6, lets you overdrive the cards over the bios limits. I dont know if they are included already in Linuxcoin, but if they are not it would be a nice addition since it removes the need to flash the bios of the cards.

EDIT: For reference: http://forum.bitcoin.org/index.php?topic=19776.msg258398#msg258398