What Conroe Model Suits Best for Overclocking?

by Aleksey Razin

[ 06/06/2006 | 05:31 PM ]

Hardware enthusiasts now have only the very first Conroe samples at their disposal, however this doesn’t stop them from researching their overclocking potential with great excitement. Not so long ago we reported about a successful overclocking attempt when the Core 2 Extreme X6800 (2.93GHz) processor with unlocked clock frequency multiplier was pushed to 5.0GHz with the help of liquid nitrogen. Of course, not all overclockers will be able to hit these heights. Firstly, far not every overclocking fan uses liquid nitrogen cooling. Secondly, the actual Core 2 Duo E6xxx processors with the limited clock frequency multiplier can very rapidly exhaust the potential of the mainboard to raise the system bus frequency. Unlimited clock frequency multiplier will only be available on Core 2 Extreme X6800 (2.93GHz) processors that will sell for at least $999.

Let’s take a closer look at the new record-breaking Conroe overclocking results that are still very illustrative. For example, this discussion on XtremeSystems.org forums led by Coolaler guy tells about successful overclocking of Core 2 Duo E6700 (2.67GHz) with B0 core stepping. He managed to reach 3.9GHz with the Tuniq Tower 120 air-cooler.

To achieve these results he had to voltmod the MSI 975X Platinum mainboard revision 2.0B, so that it allowed to increase the Vcore to 1.78V. In fact, the CPU also worked at 4.0GHz, however, the benchmarks couldn’t be completed at this speed without losing the system stability. Anyway, we assume that it shows clearly that the top models of mass production Conroe CPUs will be able to overclock to 4.0GHz with air-cooling.

I would like to specifically stress the words “top models”. Take a look at the screenshot: with 10x clock multiplier the system bus frequency equals 390MHz. it is a pretty high value and the slower is the processor model, the higher this frequency should be to reach the maximum core potential. Core 2 Duo E6700 (2.67GHz) will cost around $350. Remember this number, as it is important for our today’s discussion.

XtremeSystems.org forums have described the first overclocking experiment with the Conroe CPU featuring 2MB L2 cache. All the previous Core 2 Duo E6xxx samples discussed featured 4MB L2 cache even if the mass production modification were to have only 2MB. Now the famous FUGGER managed to get his hands on a Core 2 Duo E6300 (1.86GHz) CPU with B0 core stepping that features only 2MB L2 cache. The CPU, however, is a dual-core one, even though we have always believed that Allendale code name on the screenshot stands for the single-core model. Looks like the so-called Conroe-L processors will be codenamed differently.

The experiment showed that even if the second core was disabled completely and the Vcore was set to its maximum, Core 2 Duo E6300 processor doesn’t allow to increase the system bus frequency beyond 477MHz. with the maximum clock frequency multiplier of 7x, it can only clock to 3.33GHz. It is not a bad result, but the mainboard should features really good overclocking-friendly options to achieve this. Most mainboards may face serious difficulties during this overclocking attempt, especially if the implemented Conroe support didn’t imply wide frequency range for the system bus.

FUGGER stopped at 3.22GHz frequency achieved with a serial Freon cooling system. With the processor Vcore at its nominal value, the CPU clocked to 2.33GHz. By raising the Vcore to 1.4V, he gained about 700MHz extra. These results, indicate once again that low clock frequency multiplier will become a limiting factor for successful overclocking of young Conroe models. The minimal multiplier is 6x, which is set by the EIST technology supported in all Core 2 Duo E6xxx. By the way, Core 2 Duo E6300 (1.86GHz) will be the youngest Conroe model launched this year. The dual-core Core 2 Duo E4200 (1.6GHz) with 800MHz bus is due in early 2007. Actually, despite the lower price, it will support higher clock frequency multiplier of 8x and lower nominal system bus frequency of 200MHz, which will make it a more attractive solution for overclockers.

Core 2 Duo E6300 (1.86GHz) will cost $183, which is almost 3 times less than the price of Core 2 Duo E6700 (2.67GHz). However, low clock frequency multiplier will shift all the load to the mainboard, which may prevent you from squeezing all the juices out of the CPU. If you intend to hit certain frequency, then it makes more sense for you to spend more money on a model from the middle of the product line-up, instead of getting the slowest one. In fact, P965 based mainboards may save you some trouble, but they will not be cheap, also. So, efficient Conroe overclocking will require some tangible financial investments.