Overclocking an old i7-6700K: hoping to eek out a little more, but not sure what to do. - Overclock.net - An Overclocking Community

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Overclocking an old i7-6700K: hoping to eek out a little more, but not sure what to do.

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post #1 of 1 (permalink) Old 07-26-2020, 10:52 PM - Thread Starter
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Overclocking an old i7-6700K: hoping to eek out a little more, but not sure what to do.

I've got an old system running on mostly 5-year-old hardware, which I'm finally getting around to OCing. I'm trying to eek out a little more life from the hardware, delaying the need to upgrade. But I'm having some issues with stability and heat that, based on what I've read about this processor, don't seem typical. So I'm hoping you folks can help me eek out a few more MHz, while keeping my CPU cool and stable.

Here's my specs:
i7-6700k @ 4.00GHz (base)
Asus Z170-A mobo
2x8GB Crucial Ballistix Sport 2666 MHz CL16 DRAM
Noctua NH-U12A cooler
Phanteks P400A-Digital case
GIGABYTE RTX 2070 Gaming OC 8G

The case and cooler are new, purchased this week because my previous case and cooler were badly set up and too loud. The RTX card was purchased after I fried my 980Ti in late 2018 .

My first attempts at OCing were met with surprising success. I was able to easily get my system to 4.4Ghz by simply bumping the multiplier and doing nothing else. I ran Prime95 torture test, and it worked great for hours, and my core temps never cracked 75C. So I went to 4.5GHz, and had similar results. Temps started climbing into the high 70s, but it seemed fine. So I tried 4.7GHz, which went well enough to try 4.8Ghz. That one finally gave me pause, as my Core 0 temp started to hit 95C, which I knew was way too much. So I went back to 4.7GHz.

In an attempt to figure out how best to drop my temps, so I could try again at 4.8GHz, I read up on how to properly OC i7-6700Ks, and I realized that I'd screwed up: I'd accidentally left my mobo's automatic VCore setting enabled. So the reason those temps got to 95C sometimes was likely due to the mobo pushing VCore way too high in its attempt to make my rig remain stable.

So I started doing it "properly", based on this guide from TweakTown. Particularly the flowchart.

Unfortunately, I got severe stability issues even at the very first OC that the chart recommends (4.5Ghz at 1.3v Vcore). Prime95 would throw a "HARDWARE ERROR" very soon after starting it, and IntelBurnTest would freeze.

After a bunch of experimentation over the weekend, and trying new stress tests, I was disappointed to ultimately settle on a 4.5Ghz OC @ 1.34v Vcore. That would pass 20 minutes of Prime95 (AVX disabled), and 15 minutes of RealBench stress testing (which I read was a better way to do AVX stressing), without cracking 85C on the hottest core (Core 0 is often 3-4 C hotter than the other 3 cores). Higher multipliers would make the system unstable, and higher voltages would make the CPU too hot (>85C at load after a few mins).

Did I just badly lose the silicon lottery? Is it because my CPU is 5 years old? Or is there something I can do to improve this?

Maybe try to apply thermal paste better? I have some Kryonaut paste from Thermal Grizzly, which I got just in case I'd need it. But my Noctua cooler came with NT-H1 thermal paste, so I used that.

Thanks in advance for any help you folks can provide!

Last edited by coredumperror; 07-26-2020 at 10:59 PM.
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