From syntax_error (mod): AGP slot/card support status: Generally... If AGP 1.0 or 2.0 card is running in 2x, 1x mode it will use 3.3v If AGP 2.0 or 3.0 card is running in 4x mode it will use 1.5v If AGP 3.0 card is running in 8x mode it will use 0.8v AGP 1.0 slot supports 1x and 2x at 3.3v AGP 2.0 slot supports 1x and 2x at 3.3v AGP 2.0 slot supports 4x at 1.5v AGP 3.0 slot supports 4x at 1.5v AGP 3.0 slot supports 8x at 0.8v AGP 2.0 and 3.0 cards and slots overlap nicely. Hardly anyone has sold an AGP 1.0 anything for a couple of years now. The only real 'bender' to these rules is that some boards based on Intel chipsets with an AGP 2.0 slot do not support 3.3v (2x, 1x) AGP operation. These boards will usually feature a large warning sticker or be keyed to not accept an AGP 1.0 card.