ultima wrote on 25.11.13 at 22:50:24:And I forgot to mention, all those benchmarks online don't show any noticable difference in performance between a pci and agp, so if it is true that the pci is tested on a 33Mhz slot, and it is almost on par with the agp, it means 2 things:
1: the agp part is just physical difference, it doesn't use agp features or it's added speed
2: if the pci really does run @66Mhz, it should be faster then it's agp counterpart, which performs the same as a pci @ 33Mhz
1: Indeed, all 3dfx AGP adaptors are basically PCI adaptors simply "ported" on the AGP bus. They don't support typical features introduced with the AGP standard, like DIME, fast writes and sideband addressing, the latter except for Banshee and Voodoo3. AGP speeds are 2x max for Banshee/Voodoo3, 4x max for Voodoo4 and 1x for Voodoo5
2: Nope, all 3dfx AGP adaptors can do at least AGP 1x (66Mhz) which is double the PCI bus and that is that. The only improvements of the AGP over the PCI when it comes to 3dfx video cards are:
-Double bus bandwidth
-Dedicated bus, it does mean that no bandwidth is shared across other devices and it's all available to the VGA.
A Voodoo5 PCI should have exactly the same performances of the AGP one *if* you can run the card into a PCI-X slot, which is a PCI slot capable of 66MHz (PCI-X=AGP@1x).
So Voodoo5 PCI and AGP are basically the same thing. Point at issue is that as long as you can put the AGP one into the slot and get the card to work you'll run always the card at 66MHz bus clock. For the PCI version, in order to race against the AGP one, you have to choose the right slot, the one capable of 66MHz instead of classic 33MHz, which is the PCI-X slot as already stated.
In the end, if you don't notice any relevant difference between Voodoo5 AGP and PCI, even when the latter is using a PCI 33MHz slot only, is beacuse more likely the application doesn't require more bandwidth as much the 33MHz bus can offer.