Intel Core 2 Duo is based on the new 45nm Wolfdale core, and long before the launch it was suggested that this core could become something of a SuperPi benchers best friend. Intel Core 2 Extreme QX9650, which is a 45nm quad-core processor, is capable of SuperPi 1M calculations in less the 7.5 seconds, if you can get it stable at 6GHz. And there’s always the option of disabling cores, but that doesn’t always help. With a native dual-core like Wolfdale it would seem easier to reach those frequencies, but the problems is the locked multiplier (9.5 at best) which forces you to push the FSB past 633MHz to break 6GHz.
German overclocker monteboy got close. He reached a clock frequency of 5789MHz (9.5×609), but that was still enough to break the 8 second barrier. He was able to reach 7.895s to be exact. If we’re reading CPU-Z correctly, he had deactivated one of the cores.
Speaking from personal experience it’s really hard to get a high clock and bus frequency stable at the same time and in this case they’re both extreme. He used liquid nitrogen and a fully modded ASUS P5K, a board which has been proven to work well for FSB overclockers.