AGP variants almost boggle the mind and make it a nightmare to match a video card to a motherboard. With rare exception, makers of video boards only tell you the "X part (1X, 2X, 4X, 8X) and nothing else. Turns out there are 3 voltages possible for use of AGP boards: 3.3V,
1.5V and 0.8V. Then there are the protocols: 1.0, 1.5, 2.0, ?2.5?, 3.0 and 3.5 . So amoung these three variations, a multitude of possibilites exist in the wild.Makers of motherboards are a bit more forward in stating what each motherboard will allow, but a number of them usually fail to disclose the protocol. To get the most complete "picture" of what a given motherboard will support, one must meticulously scan thru sometimes incomplete and sketchy motherboard "manuals", BIOS manuals, and reports (if any). And even then, most times the information will be incomplete.
As a result, research makes it virtually impossible to determine, on the basis of specifications, whether a given video board will actually work on a given motherboard. One my wind up getting 6 different video boards "that will work" (according to seller) only to find that none of them work - never mind you tried 2X, 4X, 8X and so-called "universal" boards of various types (2X/4X and 4X/8X).
Makes one wonder if done on purpose. Manufacturers, when asked if a given combo will work have ZERO comment.