Just built my new system with the ASUS 4870x2 and when I logged in everything was great. Set EVERYTHING to max. Once in a quest though, crashed as soon as we hit major action.

Updated MB Bios. Updated MB drivers. Updated Vid drivers. Updated sound drivers.

Still crahsed.

Checked the Mod 8 known issues. 4870's crash with stencil shadows on. Turned it off, no crashes at all now. Lesson learned. Check the known issues first...