Lynnfield Overclocking Peculiarities
We anticipated the arrival of the new processors with mixed feelings. On the one hand, we were extremely curious to see what they are capable of in tests, find out how Lynnfield different in functionality from the junior Bloomfield and top Core 2 Quad. We were already excited about the new Turbo Boost implementation, because Lynnfield are the first universal processors that combine the advantages of multi-core and single-core CPUs. They work as multi-core processors in contemporary multi-threaded applications: run at not very high frequencies but execute multiple computational threads at the same time. They lower the number of active cores putting uninvolved ones into energy-efficient modes when there is no need for multi-threading, thus increasing the working frequency of the remaining active cores quite substantially. On the other hand, we had some logical concerns. How do we overclock processors, which frequency multiplier can increase by 4-5 points above the nominal setting? Keeping in mind that in idle mode the multiplier lowers to 9x and under heavy load increases to 24-27x, it seems barely possible to determine operational stability in all intermediate modes.
Luckily, it turned out that new processors can be overclocked just as easily as any other CPUs, and maybe even easier. Unlike LGA1366 platform, now we don’t have to monitor the frequency of the North Bridge part integrated into the CPU, which is called Uncore according to Intel or IMC (Integrated Memory Controller) according to Asus. Secondly, overclocking no longer requires serious IMC voltage increase. Before, we were offered to increase this voltage to 1.5-1.6 V in order to ensure that our memory could work at high frequencies. In reality we could often do by raising this voltage to 1.35-1.45 V, which was still pretty high. Now we don’t have to raise the IMC voltage at all for the memory to work at high frequencies, and for stability at 200 MHz base clock it should only push it to 1.2 V.
Just like with Bloomfield processors on LGA1366 mainboards, there are two ways of overclocking Lynnfield. The first way is the static implementation of Intel Turbo Boost technology, or even its complete disabling. In both cases we deal with a system where the processor clock frequency multiplier remains locked at a certain fixed value under heavy load. It is either at its nominal value if we disable Turbo Boost completely, or is a little above the nominal independent of the processor load. The second overclocking approach is dynamic implementation of Intel Turbo Boost, when the multiplier depends on the current processor utilization. The fewer cores are busy, the higher rises the multiplier, and the other way around.

It is clear that both these approaches have the right to exist. The static implementation is good for those users who work with well-paralleled applications – programs that can perform multi-threaded calculations that speed up the process a lot. Among them are applications for distributed computing, creation and processing of multimedia content: multi-threaded tools for work with models, sound, images and video. Dynamic overclocking approach will suit more for a home systems used for everyday work and entertainment. In this case we benefit most from the use of single- and dual-thread applications, which are still the majority these days and at the same time ensure very high performance level in multi-threaded tasks.
However, it all looks so simple only in theory. In reality we didn’t manage to find a universal LGA1366 mainboard that could have both versions of Intel Turbo Boost technology implemented equally successfully. We have most often seen mainboards only with static implementation, and more rarely – only with dynamic one. If we had a mainboard that allowed us to choose either of these, then again only one of the implementations was a preferred one. As for LGA1156 mainboards, looks like they simply do not have a problem like that at all. By default, all mainboards are set for static implementation of Intel Turbo Boost technology, and if you wish to enable the dynamic one you have to enable extended C3-C7 modes in the BIOS Setup section with processor settings.
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Before any overclocking experiments we have to do some preparatory work. First of all, it would be really good if you could remove the “Auto” settings for all significant parameters in the mainboard BIOS. No one knows at what stage the mainboard suddenly decides to increase the voltages, change the memory frequency or timings, which may have a negative effect on system stability. That is why we lower the memory frequency right from the start - it will increase as the base clock frequency increases – and we will find out the end-value a little later when we make our decision regarding the CPU overclocking. As for the major timings, it would be best to set them to guaranteed operational values, for example, 8-8-8-22 or 9-9-9-24. All voltages should be at their nominal values, except the IMC voltage, which can be increased to 1.2-1.25 V right away (we will lower it later on if we don’t need this increase), and the memory voltage, which should be raised no higher than to 1.65 V. as for the processor Vcore, we can also leave it at its nominal, of you prefer to have a fast but at the same time energy-efficient system in the end. Do not forget to enable ”Load-Line Calibration” technology preventing the processor Vcore from dropping under heavy load. On the other hand, you can increase the voltage right from the beginning, but the increase really depends on the efficiency of your processor cooling.
As the first step towards overclocking, you can double-check that the mainboard can remain stable at high base clock rates. In fact, we do not expect any problems here, all LGA1156 mainboards we have worked with so far performed stably up until 210 MHz base clock frequency. However, it is best to make sure this is the case instead of guessing later on why the CPU doesn’t overclock any higher simply, to find out that the reason lies with the mainboard. Therefore, let’s lower the processor clock frequency multiplier to 12-14x, so that its frequency could be close to the nominal during maximum overclocking. After that we raise the base frequency to 200-210 MHz. at this point we have to check if the memory frequency really lies within the acceptable range for the installed memory modules. And finally we use any test program to run a stability test. If you have hard time deciding on a program like that, we can recommend Prime95. At this point you can lower the IMC voltage, if possible. If lower voltage setting will be acceptable at these high base clock speeds, then it should definitely work at lower base clocks as well.




