775Dual VSTA not working w/ x800xl AGP

[dr.zapp]

I have an x800xl AGP card that works fine on a DFI NF3 Lanparty 250GB, but will not work on 2 different 775Dual VSTA motherboards, with the 3.15a, 3.17a or 3.19a BIOSes. I have tried changing everything to do w/ the AGP in the BIOS, but no luck. The board boots, and displays "x800xl" in the upper left corner and a cursor under it, but nothing else. The computer however, continues to boot into XP, as I can hear from the XP startup sound! My x1950 XT AGP works in both 775Duals. On two occasions I have gotten the x800xl to get past the initial "x800xl" text long enough to get into the BIOS, but it went back to not working on reboot. Both times I had turned on the computer w/o the x800xl plugged in, saw the flashing warning about plugging it in, turned off the computer, plugged it in, and then it started fine. This is NOT consistently reproducible, however... 2 times in ~50 tries. I am out of ideas here... anyone else solve this?