A neat hardware article has been posted by Motherboards.org. It explains the technical background of AGP 1x, 2x, 4x, AGP pro, and AGP 8x. They also have AGP connector charts. Here's a snip: The AGP interface specification uses the 66 MHz PCI (PCI Local Bus Specification) specification as an operational baseline, and provides four significant performance extensions or enhancements to the PCI specification which are intended to optimize the AGP for high performance 3D graphics applications.