I have spent some more time with that setpci on the DPW600au. All cards in my system have this flag on by default - except the 3dfx - and I can clear and set this flag and others wherever I like - except on the 3dfx. Swapping the card into other slots doesn't help. If nobody has ever seen a running and working 3dfx 4500 (or 5500) (with DRI) on an Alpha, I'm going to scrap this device and watch out for a Radeon or something. Urs