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Overclocking

After our experience of overclocking Haswell-based CPUs we had high hopes about the overclocking potential of the updated LGA2011 platform. The problem with the desktop Haswell-based CPUs is that they have inferior thermal interface material between the CPU cap and the CPU die. It is therefore difficult to cool them - they quickly overheat when overclocked, so their overclocking potential is far from impressive.

It’s different with the LGA2011 CPUs. Intel employs fluxless soldering for them, so the CPU die transfers its heat to the CPU cap via indium-based solder. That’s why the success of your overclocking an Ivy Bridge-E CPU depends on your cooler's efficiency and is not limited by any other factors.

As for the overclocking tools the new CPU design offers, there are almost no differences from the Sandy Bridge-E. Each Ivy Bridge-E processor has an unlocked frequency multiplier while the base clock rate can be set at 100 or 125 MHz (and also at 167 MHz in some cases). The memory frequency can be adjusted with a step of 266 MHz up to DDR3-3200 mode when the base clock rate is 100 MHz. When the latter is 125 MHz, the adjustment step is 333 MHz.

In fact, there are only two overclocking innovations in the Ivy Bridge-E. The new CPUs support real-time overclocking (without rebooting to apply new parameters) and the maximum multiplier is now x63.

Let’s see what practical results can be achieved by overclocking Ivy Bridge-E processors. We should note that we don't want to set any overclocking records. Our goal is to find the peak frequency the CPU can work at continuously in 24/7 mode. That's why we restrain our voltage adjustments, use a single-section tower-design cooler Noctua NH-U14S, and keep the CPU temperature below the throttling threshold (which is set at 95°C for the Ivy Bridge-E).

So, the quad-core Core i7-4820K turned out to be the most overclocker-friendly CPU in our tests. Its result is quite exceptional in comparison with the new Haswell-based CPUs: it can work at 4.8 GHz and a voltage of 1.375 volts.

The peak temperature of the CPU cores varied from 78°C to 88°C when running the AVX-supporting LinX 0.6.4. We thought that was quite acceptable since the Core i7-4820K has a higher thermal throttling threshold (100°C) than its six-core cousins.

The midrange model Core i7-4930K wasn’t so successful. Its six cores generate much more heat, calling for more advanced coolers, perhaps even liquid cooling systems. Using our air cooler Noctua NH-U14S, we had to content ourselves with 4.6 GHz at a voltage of 1.325 volts.

The CPU cores had a temperature of 74°C to 83°C at high loads. Moreover, to ensure stability of our Core i7-4930K, we had to increase its uncore voltage to 1.2 volts.

The senior LGA2011 processor Core i7-4960X (from the Extreme Edition series) gets much hotter than its cousins when overclocked. That’s why its end result is lower. When its core and uncore voltage was increased to 1.35 and 1.2 volts, respectively, we made the CPU stable at only 4.5 GHz.

It doesn’t mean that this is the maximum our Core i7-4960X can do. We just had to limit ourselves to that frequency with our cooler to avoid overheat: the temperature was already as high as 75°C to 85°C.

Summing it up, the updated LGA2011 platform really pleased us with its overclocking potential. Besides the higher maximum frequencies (in comparison with the Haswell generation), the Ivy Bridge-E, just like the Sandy Bridge-E, is overclocked in an easy and comprehensible way. You increase its clock rate, add more voltage to improve stability, and make up for the increased temperature by using a better cooler. That's the recipe. There are no hindrances or pitfalls as with the Haswell or Ivy Bridge CPUs for the LGA1150 and LGA1155 platforms. It is a huge advantage of the LGA2011 platform that appeals to overclockers.

As for the frequency potential of Ivy Bridge-E processors in comparison with their Sandy Bridge-E predecessors, there are no fundamental improvements. Although the new LGA2011 products are manufactured on Intel’s most advanced 22nm technology, they cannot reach 5 GHz with air cooling. Still, the LGA2011 platform is a good choice for enthusiasts and overclockers who are going to run their Ivy Bridge-E processors with more efficient coolers than ours and thus achieve higher clock rates.

 
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