Adjusting the AGP speed multiplier and Fast Writes can stabilise your AGP port. Typically, both the motherboard and the AGP port are initialised to the highest speed multiplier each can support when shipped. This could be 8x, 4x, 2x, or 1x. The speed multiplier can be adjusted through either the BIOS or configuration software that came with your graphics card.
It is preferable to use the configuration software, as that will be more specific to your card. Choose a speed below the current AGP speed setting. You may have to reboot the system for it to take effect. Sometimes, the software will not apply the change, so once you’re back in Windows, go back to the software and verify that the speed has been changed. If you’re not able to change the speed through the software, use the BIOS to change the speed.
If Fast Writes are enabled by default in your BIOS, leave them enabled and reduce the speed multiplier. If the system still shows instability, then disabling Fast Writes will most likely solve the problem. The reverse also applies: if Fast Writes are disabled by default, leave them disabled. Reduce the multiplier and check for stability. If system is still unstable, then enable Fast Writes. Note that some graphics cards refuse to work with Fast Writes disabled.