AMD Phenom II: Overclocking with dry ice

In a demonstration AMD showed that the Phenom II can reach clock speeds up to 4 GHz running on air cooling and in diverse OC forums screenshots of frequencies higher than 6 GHz have been published already. While the predecessor of the Phenom II often wasn't stable with 3.4 GHz and could reach the 4 GHz region with dry ice cooling only, it seems like the 45 nanometer Phenom has remarkable overclocking capabilities.

AMD Phenom II X4 940 BE
The Phenom II X4 940 BE has, like most CPUs of AMD's Black Edition, an open multiplier. This is quite useful for overclocking experiments because the frequencies of the CPU can be adjusted independently from the memory and reference clock speed. Since the reference clock is 200 MHz low, the multipliers of AMD's CPUs commonly are quite high. Accordingly the frequency steps are rather big when the multiplier is increased. For fine tuning the reference clock has do be increased by a few Megahertz.

More about the Phenom II X4 940 BE can be found in our Phenom II review.

Cooling the Phenom II
In order to reach higher clock speeds we had to cool the Phenom II X4 940 BE below the freezing point. We used pellets of dry ice which were provided by the company Enotech for free. To prevent damage from condensate the CPU socket and the area around it have been isolated. Bedsides the dry ice a small amount of isopropanol was filled into the special cooler of Andreas "Otterauge” Zelba - in order to increase the cooling surface.