Aida32 or it's replacement, Lavalys Everest Home, can normally tell you precisely what you want to know.
No bothered to update yet, but I'll chuck the latest beta of Lavalys Everest in, and screenshot the appropriate area.
New today, downloading, back later!
AGP 1.0 - Speeds 1x/2x, Voltage 3.3v only
1.0 cards require 3.3v support and are unsuitable for modern motherboards
1.0 motherboards (3.3v) require a "universal" card that supports 3.3v operation and AGP 1.0 - some cards that do support it, may still have issues with some motherboard chipsets.
AGP 2.0 - Speeds up to 4x, Voltage 1.5v (where "dual", should also support 3.3v operation for lower speeds) - modern motherboards tend to drop 3.3v support, from quite some toime back.
AGP 3.0 - Speeds up to 8x, Voltage 1.5v with 0.8v signalling - most AGP 2.0/3.0 components are fully interchangeable