I'm having the exact same issue as kotix. I have the AGP card with NV41 core. NV41 has 12/5, but this XFX 6800 XTreme is only allowing 8/4. No luck unlocking, and I get the same N/A as kotix posted.
I've read that the NV41 is a pci-e native chip, and a bridge was needed to make this an AGP part....I wonder if they were able to lock it through that bridge? I dunno. Was really hoping to get 12/5, but am satisfied with the performance for the price I paid.
However, if anyone has learned how to overcome this obstacle, please let me know!
SD