Just so you can exclude the driver being too old, I suggest you go to this thread and get LinuxCoin. You have there a video tutorial and if you read on you'll see exactly how to create a USB disk from the ISO file (you can do it in Windows pretty easy). I can vouch that my 5830 xtreme can be overclocked to 1020 without BIOS editing, using LinuxCoin and the commands that I pasted.
If it still doesn't work, then it's hardware related and you might want to edit your BIOS.
I dont want to jump ship and use what there is limited support for.. not many use linuxcoin. I will go about editing the bios.. I gotta shutdown thee old machine.. slap in a hd install windows and use this rbe editor and then bootup off the usb key and remote back in and see whats cookin in the kitchen.