Riser Card 27.3 mm. PCI-Express adapter 8X to 16X - Cablematic
history - Was AGP only ever used for graphics cards? - Retrocomputing Stack Exchange
What is PCI Express?
Oscar Barea on Twitter: "3Dfx Project AGP to PCIe - Perhaps 3Dfx fans can be interested but I am really busy and lazy. It is AGP2PCIe adapter. Design is ended since summer