Wednesday, July 9, 2014

Overclocking my Devil's Canyon Core i7 4790K

2014-07-05 13.29.51

It's Haswell overclocking all over again. In the previous post I mentioned that I was able to boot into Windows at 4.6GHz with just 1.25V for Vcore with my new Devil’s Canyon chip. I ran OCCT for just a minute and felt great about it as it is did not crash. But I indeed did not run long enough. I wanted to see if it can do better.

Next I tried 4.8GHz at 1.25V. Alas, it gave a BSOD while booting Windows up. Sigh! Then I increased the Vcore up to 1.30V and tried. This time it booted into Windows without any drama. But OCCT crashed instantly. Again, sigh! So it definitely is not a super chip.

Then it was time to start overclocking properly. The stress test of my choice was OCCT 4.4. While it is not as hardcore as Prime 95, which at version 28.5 seems to be an impossible stress test to pass without delidding - even with the "Next Generation Polymer" based thermal paste that Intel is claiming which performs much better than the crap that they use with non-Devil's Canyon parts. Since it seems that I would be stuck with this CPU probably until I leave Japan for good, I didn't want to see it degrade. Hence, this time around, I am very conservative with the length of stress tests and how much heat I put it through.

While I know that the CPU must be well capable of at least 4.6GHz, I wanted to start low. I dropped the multiplier to 44x, Vcore to 1.2V, set memory speed to XMP, set Ring voltage to 1.1V and let everything be automatically determined by the motherboard. This set the Uncore multiplier to 40x and Input Voltage to 1.75V. And this deemed stable in OCCT. Good! Now, we have a starting point. It is possible that the CPU didn't need 1.2V for Vcore, but I didn't want to check the absolute best. I only ran OCCT for like an hour.

4.4GHz settings

  • Vcore: 1.20V
  • Ring Voltage: 1.10V
  • Uncore multiplier: 40x (AUTO)
  • Input Voltage: 1.75V (AUTO)
  • Load-Line Calibration: Level 8 = MAX (AUTO)
  • Memory: XMP (2400MHz/11-13-13-35-2T/1.65V)

Next stop was 4.5GHz. I tried same settings, but it gave a BSOD. Sadness!. The first thing to do after that was to raise the Vcore. While keeping everything the same, I could achieve stability at 1.23V of Vcore. That's decent. I needed 1.25V at 4.3GHz with my old CPU and it was never stable at 4.4GHz. However, to my surprise, the max temps reached 90C on one of the cores.

4.5GHz settings (preliminary)

  • Vcore: 1.23V
  • Ring Voltage: 1.10V
  • Uncore multiplier: 40x (AUTO)
  • Input Voltage: 1.75V (AUTO)
  • Load-Line Calibration: Level 8 = MAX (AUTO)
  • Memory: XMP (2400MHz/11-13-13-35-2T/1.65V)

Next stop was 4.6GHz. Getting 4.6GHz stable deemed almost impossible with my current cooler. With a Vcore bump alone, I couldn't get the CPU stable even at 1.285V and the temps were reaching almost the TJ-max. Therefore, the Vcore couldn't be increased any further. That's when I decided to hit the forums, to ask away how to proceed from here after. One guy offered to help me via PMs. He gave me some settings to try out. They indeed were radically different from what I thought I might need, especially when the 4.5GHz overclock didn't require much tinkering. He asked me to drop the Uncore multiplier to 35x (from previous 40x) and memory clocks (from 2400 to 1600) for now, until I got the "core overclock" sorted out. The other settings were, Vcore = 1.27V, Ring voltage = 1.15V (despite dropping the Uncore multiplier) and to try out 1.8V, 1.85V and 1.9V for Input Voltage and use what seems to be the most stable. Finally I managed to get it stable in OCCT at an Input Voltage of 1.90V, but OCCT terminated the stress test after 53 minutes as temperature of one of the cores reached 95C, the temperature limit I had specified in settings. By the time of writing this post, there wasn’t enough time to further lower the voltages or run Handbrake to see if it is truly stable.

4.6GHz settings (preliminary)

  • Vcore: 1.27V
  • Ring Voltage: 1.15V
  • Uncore multiplier: 35x
  • Input Voltage: 1.90V
  • Load-Line Calibration: Level 6 (this keeps the Input Voltage at 1.904V)
  • Memory: 1600MHz/11-13-13-35/1.65V

I'll definitely be tweaking the settings - voltages, Uncore frequency and Memory settings - when I get some free time. But there is a bigger problem at hand. What the heck is wrong with my cooler?

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