Not sure yet if its down to some boards but both my box and telsa's i815 based box keep hanging (entire box) when running XFree86 4.1. Its at the crashes every day or two so is completely unusable stage. In my case this is the same box I reported 3dfx hangs on - although I saw 3dfx problems a while back with an older XFree and an AMD board that looked very similar. Interestingly it looks like both may have crashed with the time of day value the same, thats a very very strange co-incidence if indeed it is chance. Any specific info you want [Celeron 800, A/Open MX3S i815 chipset, RAM has passed memtest86]
By way of more info. I tried a known stable G200 setup on the MX3S and that hung solid too. I've now moved the problem 3dfx card into a VIA chipset board with the same CPU etc installed, and will see if these are MX3S hardware problems again (I've returned several faulty MX3S boards so its quite possible the board simply sucks).
Just config file + server log, and also 'messages' if it offers any clues, DRM debug or errors, etc..
Total hang, dead board, dead everything, even dead to poweroff Board returned