Look my friend.
I have the same problems with some directx games: this is the list:
Other directx games run without a problem:
all the 3d mark, all resollutions, all settings max
All the opengl games run too damn good!!
I have tried a lot of things, except updating my bios,. maybe this weekend , or if i cant play the unreal 2003 demo.
so i think the problem is not the video card, neither the mobo, but a bug in the game . Im not sure, anyway, and if somebody fix this weird problem , i hope that drop us a line!!!
This is not a problem for me since im not playing now a directx game, but neverwinter nights.