Why is AGP 6600gt showing up in nvidia properties as 0x PCI?

[btbam]

It's an 8x AGP card, and it's showing up as 0x PCI?

 

[DusterAZ]

Probably because it uses a PCI-E to AGP bridge versus having native AGP like the 6800 series. Probably just confusing the driver. Not sure which driver you are using but maybe the 67.03 will change that but it is simply cosmetic.