When we just started working on this material, we expected to overclock the youngest Intel Core 2 Duo model to phenomenal heights. And we had very good reasons to believe so. The thing is that there are a lot of overclocking reports on the web these days about successful overclocking of Core Microarchitecture based processors. And in most of those stories the users managed to nearly hit 4GHz frequency with none other but air cooling. If the youngest Core 2 Duo E6300 processor with 1.86GHz nominal frequency manages to hit this mark, we will be able to claim unprecedented result: doubling of the CPU speed.
However unfortunately, our expectations didn’t come true. The thing is that the clock frequency multiplier of Core 2 Duo E6300 processor is locked at 7x. That is why we would have to increase the FSB frequency to 571MHz in order to hit the 4GHz core speed. And this isn’t possible for at least two reasons. First, the current clock frequency generators allow overclocking the FSB up to 500MHz maximum. Second, the mainboard should use only super-high-quality components and be designed very thoroughly to ensure that it can retain stability at these speeds. If the second obstacle doesn’t seem that drastic, then the first one is still insurmountable.
However, we stumbled upon some problems long before the FSB speed hit 500MHz mark. And our experiments with ASUS P5W DH Deluxe mainboard revealed it very clearly.
Before we start sharing the obtained results, let me say a few words about the configuration of our test platform. Besides the Intel Core 2 Duo E6300 processors and ASUS P5W DH Deluxe mainboard we also used 2 GB of DDR2-800 memory: Corsair TWIN2X2048-6400C4. The system was also equipped with PowerColor X1900 XTX 512MB graphics card. The processor was cooled down with a Zalman CNPS9500 LED cooler, although this was an absolutely unnecessary measure, because the heat dissipation of Core 2 Duo processors is much lower than that of NetBurst based CPUs.
As for the actual Core 2 Duo E6300 processor overclocking, it was performed in a pretty traditional manner. In other words, these CPUs can be overclocked as easily as their predecessors. Especially since the frequency potential of Conroe processors is really huge.
Nevertheless, during our overclocking experiments on ASUS P5W DH Deluxe mainboard we faced two typical problems that may become the main stumbling stones for those who will ever try overclocking the youngest Conroe models.
The first problem surfaced when we got close to 400MHz FSB frequency. Any further frequency increase would prevent the mainboard from booting. It had evidently nothing to do with the CPU, because Vcore increase didn’t affect the situation in any way. We discovered, however, that at this high bus frequency chipset North Bridge fails, although Intel uses pre-selected most stable and reliable chips for its i975X core logic. The problem can be resolved easily by raising the chipset MCH voltage.
Therefore, you should make sure that the i975X mainboard you choose for overclocking experiments with the new Core 2 Duo processors allows increasing the voltage on the chipset North Bridge. At the same time, you should also check the North Bridge cooling system. When the FSB frequency increases significantly, as well as the MCH voltage, the North Bridge chip may get really hot, and even reach dangerous levels if the cooling solution is not efficient enough.
The second problem we encountered during Core 2 Duo overclocking is very closely connected with the first one. Although the MCH voltage increase improves the mainboard overclocking potential, we still wish we could squeeze more out of it. On average, every 0.05V increase results into additional 7-8MHz. As a result, if you want to use up the entire clock generator potential that theoretically supports up to 500MHz FSB frequency, you should raise the voltage on the chipset North Bridge up to 1.85-1.9V. The maximum voltage setting allowed in the mainboard BIOS Setup is only 1.65V. This is the major limiting factor for successful Core 2 Duo overclocking.
As a result, if we set the chipset North Bridge voltage to the maximum, the mainboard would work stably only at 420MHz FSB. We couldn’t get beyond this value for the reasons described above. As for the CPU, its frequency potential was very far from being exhausted. Even with the clock speed of 2.94GHz that was reached as a result of our overclocking experiment, it was still working absolutely stably at its nominal Vcore.
However, I don’t think you should be upset about the not very high frequency we achieved today. Core 2 Duo E6300 overclocked on ASUS P5W DH Deluxe by more than 50%, which is a very good result. At the same time we managed to surpass (though not tremendously) the nominal frequency of the top-of-the-line model in the family – the Core 2 extreme X6800. Keeping in mind relatively low influence of the cache memory size on the overall performance, we can state that for less than $200 you can get a CPU running close to a top end chip.
Although there are some cons to this as when we decided to see what would happen using our phase change cooling to cool the CPU down to -70c, we managed to get the Core 2 Duo 2.4 above 4.2 Ghz on the ASUS P5W DH Deluxe. However when the phase cooler broke it failed to turn the test pc off before the Duo chip had met it's maker!