I just found the answers to my questions
AGP?
Perhaps one of the most interesting aspects of the Voodoo5 5500 AGP is, well, its lack of AGP. Take a look what we said in our Voodoo5 5500 review.
The chip is an AGP 4X part, with support for AGP 2X, AGP 1X and PCI operating modes. In spite of this the VSA-100 does not support AGP texturing. 3dfx still feels that AGP texturing is not truly beneficial and thus there is no reason to pursue support for it with their products.
What does this mean? Essentially it means that the Voodoo5 5500 AGP really is not a true AGP card after all. Sure, it operates at 66 MHz, but it does not take advantage of the biggest AGP feature: AGP texturing. Without the AGP texturing, running the Voodoo5 5500 in an AGP slot is like running it in an overclocked PCI slot, as the only difference is the speed at which information travels to and from the card, 33 MHz for the PCI version and 66 MHz for the AGP version. This means that the card is basically running in a 66 MHz PCI slot when in an AGP slot. In a bit we will take a look at the benchmarks and see how much of a difference this 33 MHz makes in game play