Intel “Skylake” Core i7 6700K CPU Overview

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Overclocking

We have become somewhat accustom to being able to eek out more performance from our CPUs with the blessing of the unlocked CPUs. I’ll be the first to admit that overclocking was never really difficult in the first place, but it has just become even easier as you only really need to focus on two things – the multiplier and the voltage. It’s simple, right? Right. Unfortunately for us, the Broadwell generation, or the fifth generation for what it matters, was dire at overclocking. In fact, anyone who was serious about overclocking remained on the fourth generation chips as they were just so, so much better. Have things changed with the sixth generation, Skylake CPUs?

I’ve got a particularly average CPU in my hands in all fairness. It’s nothing special like some of my team have, but that’s just my luck. Silicon lottery and I do not mix together very well. My luck is sort of like pouring Fanta into your cereal instead of milk… it doesn’t work! Anyway… overclocking the 6700K is generally expected to bring you anywhere from 4.6 to 4.8 GHz on most average CPUs. Mine is in the upper band of the average chips as it topped out at 4.8 GHz. 4.9 wasn’t stable under 1.5 volts which is more than I was willing to put through it.

One thing which people worry about is the thermal properties of the Intel CPUs since they stopped soldering the die directly to the Integrated Heat Sink (IHS), which was due to some rather frustrating little problems. Research has been done by an independent overclocker, named der8auer by his alias, and he discovered that Intel isn’t actually choosing not to solder these by choice. The issue is that due to the size of the die, and the way that it is made, means that it the solder would eventually form micro cracks, thus becoming utterly useless and allowing your temperatures to skyrocket, resulting in a failed CPU. Enthusiasts are willing to risk their warranty and de-lid their CPUs in order to bring the temperatures down. That means that they remove the IHS and use their own thermal paste. I’ve done it on mine, and it gave me an extra 100 MHz at the same voltage, and the temperatures dropped by 8 – 10 degrees Celsius across all four cores. Why don’t Intel do it, I hear you say? Well, imagine spending 1 penny per chip more, and multiply it by as much as one hundred million CPUs. It all adds up, and results in lost profits. It would also encroach on their X99 line up, which are soldered (bigger die area).

Temperatures remain in check if you have a decent cooling system. I personally use a custom loop with a 140mm radiator, a DDC Ultra pump and an EK Supremacy EVO block. My chip will happily do 4.8 GHz at 1.45 volts and not even hit 75 degrees Celsius, fully loaded, with Intel’s own XTU benchmark. My CPU is now de-lidded, and it doesn’t even touch 65c whilst under the same conditions such as the ambient temperature and the cooling system. This is a definite improvement over Haswell, as that would regularly hit into the 80s under the same conditions. Thankfully, it was corrected (slightly) with the Devil’s Canyon re-release of the Haswell chips, but it still wasn’t optimal. Now, however, things are better and looking good for those who do not want to void their warranty to get better temperatures out of their CPU.

One area that I would like to touch on specifically is the RAM overclocking. The DDR4 controller on the Skylake CPUs is Intel’s second generation, as X99 came first and Skylake came second. They’ve had some time to improve it and to make it much stronger. Overclocking an Intel CPU is rather dull now since the removal of the BCLK/FSB system. I know you can do it now, even on locked chips thanks to a bug (yeah, Intel mess up on occasion as well!) in the microcode. However, the most fun (to me) is in the tweaking of the DDR4 memory. There is almost an unlimited amount that you can tweak your memory, as with other platforms, but it is the best part of an overclocker’s experience. If you’ve got some of the new Samsung based RAM like I do, either E-die (older) or B-die (newest), then you can get some crazy, crazy clocks. Push the volts (Samsung loves it, just like their DDR3 modules) and watch the frequency go up as the timings go down simultaneously – 4000 MHz (also known as 4K to us) can be done at 12-12-28-1T timings, which is just madness. It’s wickedly quick, but rather difficult to get chips to do it; again, the silicon lotto comes into play here once more.

 

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