ok, i tried the stable ati tool and at 4 mhz over stock gpu the cube exploded and i had yellow streaky crap everywhere, not just inside ati tool. attempt number 2 was made with the latest beta which just locked and rebooted my pc at 23mhz over core stock speed. any clues ?? its a powercolour X1800XT 512mb crossfire master card on cat 6.2.