Hi,
The game runs very smooth at extreme settings. However, after about 5 minutes in the game there is a strange green flickering and the framerate drops. Additionally the screen goes black sometimes. I do not think that the graphics card is defective because I do not experience these errors in any other game. These are my system specs:

Intel(R) Core(TM)2 Quad CPU Q9550 @ 2.83GHz
4,00 GB DDR2 RAM

I already have the latest nvidia drivers.

redownload the driver. it sounds like the card is not stable.

Same problem as before. I believe that on extreme settings the card gets too hot because the fan somehow only works at 50%.

Overheating card. Check airflow in your case.

Thanks for your help guys! I added a second 120mm fan and now everything works fine.