What are your GPU temps? Grab Ik8FanGui from here ( http://www.diefer.de/i8kfan/index.html ) if you don't have a fan/temp. monitor utility. Mine shuts down at 445 core w/o any artifacts and a GPU temp. of 45°C, so it could just be that your GPUs power handling is weak. If your temps are high ( above 70°C ), I'd say it is time for a system cleaning and a copper plate mod.
2/15/06 at 3:21pm