Three days ago I installed a Zalman VF700-Cu on my Sapphire X800 GTO2. Before installing the Zalman VF700-Cu, the GPU was mostly stable at 540 and wouldn't crash until reaching at least around 560. After installing the Zalman VF700-Cu (with Arctic Silver Ceramique) the GPU will crash on artifact scanning in ATITool as it approaches 530, despite having a lower GPU temperature. My max memory overclock did go up a little, though. I left the existing heatspreader installed and I'm only using half of the ramsinks for now and thinking of possibly putting the rest of them on the heatspreader (http://forums.techpowerup.com/showthread.php?t=8010). Any ideas on what could have gone wrong such that the temperatue is shown lower, but the max GPU overclock would go down?