The AGP bus carries only two components, the AGP video card and the motherboard's chipset, so a large amount of the 528MB/s of bandwidth is available for video card usage.

So a PCI card has to compete with several other components such as a sound card, ethernet card, modem, SCSI card, MPEG-2 decoder, and possibly more, all for 132MB/s of bandwidth. Meanwhile, an AGP card has all of 528MB/s of bandwidth to share only with the chipset. The AGP bus has a clear advantage here.

So as we can see, AGP has many advantages over PCI. Four times the bandwidth, a more efficient usage of that bandwidth through pipelining and sidebanding, DIME on textures, and an unshared bus make AGP the clear winner over PCI…at least on paper.

But how about in the real world? Do all these advantages translate into real performance improvements? First, let's take a look at the card we're reviewing, the Voodoo3 3000 PCI.

The card's core is a .25micron Voodoo3 3000 graphics chip running at 166MHz topped with a large aluminum heat sink. Connected to the core via a 128-bit memory bus are eight 2MB 6ns SDRAM modules, for a total of 16MB of SDRAM that are also clocked at 166MHz. According to 3dfx, the card has a theoretical maximum fill rate of 333MegaTexels per second (those are bilinear textured pixels) with a 7 million triangle/second maximum throughput. This puts the Voodoo3 3000 PCI nostril to nostril with its AGP bussing brother. The only gaping hole in the feature-set is a lack of 24-bit or 32-bit 3D support. Another thing it is missing is the SVHS out that the AGP Voodoo3 3000 has, though most people do not use SVHS outs.