Tuesday, August 13, 2013

[Article] Overclocking my 4770K – breaking 4.3GHz

You must be wondering why I want to overclock a super fast CPU like the 4770K. Fun, man, fun! No other reason. All the chips that I have had so far, maybe not my Core i5 750 which clocked +50% at stock volts, have been poor to average clockers. My previous 2600K CPU needed about 1.34-1.36V for 4.5GHz.

Unfortunately, my 4770K chip doesn’t break that spree. When it comes to Haswell, there is a simply criteria for checking whether the CPU is a good one or a bad one. If you can boot to Windows with 4.6GHz with just 1.2V, then you have a very good CPU. If you can do that with 1.25V, still your chip is above average. So the first thing I did was to set 4.6GHz and 1.2V in BIOS and check if it can boot into Windows. Nope, it couldn’t. I was greeted with a BSOD just before Lock Screen. I checked 1.25V. Still no go. Dreams shattered!

So I set 4.2GHz and 1.2V and slowly went up. With a lot of testing, I found out that 4.3GHz at 1.24V was stable enough for my liking. This is not the end of everything as I had to lower the cache ratio to 35x and memory clock to 1333MHz SPD. That sucks, but none of them can match the benefits of a 100MHz overclock on the core. Besides, you can increase them later and find the sweet spot. Right now I am only concerned about core clock. 4.5GHz is my ultimate goal, but from the way things are going, I might not be able to get there without a de-lid.

To summarize, here are my 4.3GHz stable settings.

  • Vcore: 1.240V manual
  • Uncore multiplier: x35 (min = max = 35)
  • Uncore voltage: AUTO (1.05V)
  • RAM speed: 1333MHz
  • RAM timings: 9/9/9/24/2T
  • RAM voltage: 1.50V
  • Extreme Tweaking: Disabled
  • EPU Power Saving Mode: Disabled
  • Everything else: AUTO

With the above settings, I managed to pass

  • Prime 95 v27.9 blend test for 6Hrs
  • Handbrake H.264 encoding for 2.5Hrs
  • Crysis 3 Multiplayer gaming for 2Hrs
  • AIDA64 stress test for 1Hr.

That’s stable enough for me. I don’t want to run Intel Burn Test or anything because if it passes Prime95, that’s all I need. The others are just for insurance.

Right now I’m testing 4.4GHz. I had to bump the Vcore to 1.28V. It passed AIDA64 for 2.5hrs. I’ve been running H.264 encoding for almost 2hrs. I haven’t been able to run Prime95. For some reason, when I ran it, the core clocks were fluctuating between 4.2GHz and 4.4GHz. I couldn’t understand why that was. Maybe some software glitch. I will check it after I finish with the H.264 encode. Maybe a simple reboot with fix it.

Hope it will be stable after I fix Prime95 issue. Wish me luck.

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