Andre Yang, a civil engineer doing his PhD. in the US obtained a high-performing Core 2 Duo E8600 processor, he succeeded in overclocking this chip to a stellar 6.70 GHz clock-speed (FSB 672.16 x 10.0). The processor uses liquid-nitrogen (LN2) cooling and surprisingly this processor was overclocked on a motherboard with the Intel X48 chipset, the ASUS Rampage Extreme when previous record-holders across several recent processors made use of either the Intel P35 or P45-based motherboards.
Source
CPU-Z Validation