We have already discussed overclocking in great detail in our article called Intel Core 2 Duo E6300 + ASUS P5W DH Deluxe: Ideal Mainstream Platform?. Therefore, today we are going to mostly touch upon the frequency potential of the top processor model on the Core microarchitecture – the Core 2 Extreme X6800. This processor features an unlocked clock frequency multiplier that is why it can be easily overclocked as far as the clock frequency potential of the new Conroe core will allow. So today we will finally be able to find out the maximum frequency this CPU can stably work at without hitting against the limitations set by the mainboard or the chipset.
Note that Core 2 Extreme X6800 that we had at our disposal features B1 core stepping. Since the mass production processors acquired B2 core stepping, we would expect the retail CPUs to have even higher overclocking potential. Nevertheless, the results we will obtain today will give us a great starting point for further analysis.
During our overclocking experiments we didn’t use any special cooling solutions. all tests were run with a popular Zalman CNPS9500 LED air-cooler.
First of all we decided to see how far we can go increasing the frequency without raising the processor Vcore. The nominal Vcore for our CPU was 1.3V.
Without any problems we got our CPU working stably with 12x clock frequency multiplier, which is one point over the nominal. With higher multiplier, the system would lose its reliable and stable operation, so further overclocking was done by raising the FSB frequency. The maximum rate our CPU worked stably at is given on a screenshot below:
So, Core 2 Extreme processor with the nominal frequency of 2.93GHz managed to hit 3.4GHz clock speed without raising the core voltage. This 16% increase over the nominal speed is a relatively good result for the top solution in the family.
However, it is definitely not the maximum. Numerous experiments suggest that 65nm Conroe core of Core based processors is very sensitive to voltage increase. Therefore, all further tests were conducted with the processor Vcore raised to 1.475V.
In this case we managed to increase the clock frequency multiplier to 13x, and the FSB frequency went as high as to 277MHz.
The processor frequency in this case reached 3.6GHz, which is 23% higher than the nominal rate. This way, we can conclude that not only the youngest processor models but also the top Core 2 Duo family member offers very good overclocking potential.
Note that there are some reports sharing even more impressive Core 2 Duo overclocking results achieved with air cooling. Of course, a lot depends on the actual CPU sample, however the performance level of the overclocked solution will definitely be unattainably high. Great overclocking potential of the Core based processors shouldn’t puzzle you. It is not only about Intel’s desire to leave some extra room for further processor models announcements within this new family. The peculiarities of new Core microarchitecture imply that they can design CPUs with different peak frequencies and different thermal requirements. So, if you forget about the maximum TDP of 65/75W and use high-quality cooling solution, Core 2 Duo overclocking may turn out more than fruitful.