8KHA+ error code 26?

I installed a new video card into my trusty 8KHA+ and it boots to error 26 with no video at all. The manual just says error 26 is "reserved".

The new card is a Sapphire X850 4X/8X AGP. I noticed that the AGP connector on this new card is different from the old one. The old one has 3 separate parts to the AGP connector, where this new card has 2. It does fit into the slot though. Is it incompatible?

Any ideas?

Thanks,
Gary