Try upping your AGP aperture size.
I had which looked like the same issue with a Radeon X800 GTO. I reset the BIOS before I rebuilt the box, so the AGP aperture size was set to 64M. Upping it to 128M seems to have fixed it. I've managed to recreate the issue several times.
Try upping your AGP aperture size.
I had which looked like the same issue with a Radeon X800 GTO. I reset the BIOS before I rebuilt the box, so the AGP aperture size was set to 64M. Upping it to 128M seems to have fixed it. I've managed to recreate the issue several times.