Maybe this is explanation: ( from webpage which you mentioned - http://www.playtool.com/pages/agpcompat/agp.html) One practical matter which must be considered is the fact that some of the original AGP 1.0 motherboards do not provide enough power to operate some newer AGP video cards reliably. For example, some of the original motherboards using the first chipsets which supported AGP (like the Intel 440LX and 440BX) can become unstable if you install video cards which draw lots of power through the AGP slot. The motherboards can't always supply the necessary current for the newer video cards. So if you're adding a video card to an AGP 1.0 motherboard then it's a good idea to install a video card which doesn't consume very much power. You can also occasionally get memory resource conflicts by installing a new AGP video card into an old AGP 1.0 motherboard. The video card will work properly until you install the display driver. Once you try to install the driver, a memory conflict shows up. The range of conflicting addresses varies from case to case. This problem is very unusual and when it happens it is rarely possible to fix it. I'm not sure exactly what causes the problem but apparently the motherboard and the video card are incompatible in some way which prevents Windows from properly assigning memory addresses to the video card. In the cases I've seen, there doesn't seem to be any way to predict from the video card chipset and motherboard chipset whether there will be a problem. Sometimes a particular video card chipset and motherboard chipset get along well and other times they don't. I'd guess that it's some kind of incompatibility caused by an outdated motherboard BIOS and possibly the video card BIOS. The one thing you can try is to flash your motherboard with the most recent BIOS. But since it's an old motherboard, the manufacturer will most likely not have anything but old BIOSes available. If you're running Windows 95, 98, or ME, it may be possible to manually assign addresses and get it to work but I've seen people try this and the process is about as enjoyable as a root canal and usually fails to fully solve the problem anyway. If you're running Windows 2000 or XP then it's probably impossible to fix because the newer versions of Windows almost always prevent you from manually assigning addresses, IRQs, etc. That's almost always true even if you select the standard PC HAL while installing Windows with the hope that it will allow you to assign resources manually. If you run into one of these memory resource conflicts then you should probably give up and try a different video card. It's rarely fixable.