I am having the same probs but i can't run any OpenGL games at all (not even in an un-stable way)
P4 2.4Ghz AGP4x
1Gb DDR RAM
ASUS Nvidia V9999 6800 Ultra (upgraded from a GF4 Ti 4600)
OS Mandrake 10 Official (2.6 kernel)
using 6111 drivers (also tried prev version - same thing)
X runs fine
Tried Americas Army, UT2004, UT - all the same - get a black screen and whole machine hangs. (not even caps lock light works) - I do get the ut2004 splash screen though
glxgears works and so do GL screen savers.
checked ASUS web site - no BIOS updates available.
I am really pissed ! No only did I spend the equiv of a new machine on this card, i also had to fork out for a 500w power supply. I was also about to fork out for a new motherboard to get the AGP 8x, but though i had better get it working first.
Anyone have suggestions for what else to try ?
If not, i may have to kill myself