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8700k won't overclock past 4.5GHz

Discussion in 'Overclocking & Cooling' started by Graptik, 28 Jul 2018.

  1. Graptik

    Associate

    Joined: 15 Jul 2018

    Posts: 14

    Hi, I recently bought an i7 8700k and am trying to overclock it to at least 4.7GHz. Unfortunately I can not get it stable at anything past 4.5GHz even at 1.4v. This is using fixed voltage. I am using OCCT to test stability and so far I have only got to 4.5GHz using 1.3v. Another thing I've noticed is that even when using the highest LLC level available, the voltage under load still drops around 0.3v below what I set in the BIOS. Temps are very good even when using 1.4v. Any help at all would be greatly appreciated.
    Specs:
    CPU:i7 8700k
    Motherboard: ASRock Z370 Pro 4
    GPU: Nvidia GTX 1080ti Founders Edition
    RAM: 2 x 8GB Corsair Vengeance LPX 3000MHz
    Cooler: Corsair H75 AIO
    Storage: 2 x 1TB
    Power Supply: EVGA 600w 80 Plus White
     
  2. acemastr

    Mobster

    Joined: 29 May 2010

    Posts: 4,713

    Location: Tampa, Florida

    Use LLC6

    Does it run 4.7ghz turbo speeds when everything in the BIOS is stock?
     
  3. Graptik

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    Joined: 15 Jul 2018

    Posts: 14

    On my motherboard LLC is the other way around and LLC level 1 is the highest. And yes it does boost to 4.7GHz.
     
  4. acemastr

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    Joined: 29 May 2010

    Posts: 4,713

    Location: Tampa, Florida

    That's good news then. Is the BIOS updated to latest?

    You say the voltage drops 0.3v? That would take it down to 1.1v, did you mean 0.03v?
     
  5. Graptik

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    Joined: 15 Jul 2018

    Posts: 14

    The BIOS is updated to the latest version. It will boost to 4.7GHz on one core but if I activate multicore enhancement, it will drop to 4.3GHz. Also, I did mean 0.03v not 0.3v sorry.
     
  6. acemastr

    Mobster

    Joined: 29 May 2010

    Posts: 4,713

    Location: Tampa, Florida

    What are your temps? Something odd is going on
     
  7. Graptik

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    Joined: 15 Jul 2018

    Posts: 14

    Temps are great, around 65c-70c in Prime 95 and OCCT with 4.5GHz 1.3v. Even when I tried 1.4v the temps only reached around 82c maximum.
     
  8. acemastr

    Mobster

    Joined: 29 May 2010

    Posts: 4,713

    Location: Tampa, Florida

    Are you using the latest OCCT and Prime? Both of them are AVX which really hammers to CPU. What AVX offset are you using?

    Try prime 26.6
     
  9. Graptik

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    Joined: 15 Jul 2018

    Posts: 14

    I have been using the latest OCCT but have been using Prime 95 26.6 already. I have primarily been using OCCT to check for stability so I'm wondering if this perhaps has something to do with it as I haven't set an AVX offset.
     
  10. acemastr

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    Joined: 29 May 2010

    Posts: 4,713

    Location: Tampa, Florida

    I have no choice but to use offset 3 on my 5ghz, it fails immediately otherwise.
     
  11. Graptik

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    Joined: 15 Jul 2018

    Posts: 14

    In Der8auer's 5GHz guide he recommends running a custom Prime 95 test with a maximum FFT size of 1344 and "run FFTs in place" checked for one hour as a stability test. Do you think this will more or as reliable as a stability test as OCCT?
     
  12. acemastr

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    Joined: 29 May 2010

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    Location: Tampa, Florida

    Prime is actually the most intensive test I believe, it'll stress the cpu more than most tests
     
  13. Graptik

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    Joined: 15 Jul 2018

    Posts: 14

    Okay I will test with Prime now then. I knew the new Prime95 versions use AVX but wasn't at all aware that OCCT did so thanks for that. I will let you know how Prime goes.
     
  14. Graptik

    Associate

    Joined: 15 Jul 2018

    Posts: 14

    Just tried Prime95. Unfortunately anything over 4.5GHz is still unstable. It's fine running prime for about 25 minutes and then it locks up and I have to restart the PC. So I still cannot get above 4.5GHz no matter what voltage and even without using AVX.
     
  15. acemastr

    Mobster

    Joined: 29 May 2010

    Posts: 4,713

    Location: Tampa, Florida

    Leave LLC on auto and try it.

    I guess there's a chance you received the worst CPU and that's the reason Intel don't put all cores on 4.7ghz turbo. That would be very unlucky though
     
  16. Graptik

    Associate

    Joined: 15 Jul 2018

    Posts: 14

    Just tried it. Using Auto LLC made the voltage drop straight from 1.35v to 1.21v as soon as Prime started. Level 1 seems to be the only halfway decent LLC setting it still drops 0.03v below what is set in the BIOS. Really losing my patience here as most people say 4.7GHz shouldn't require anything but the multiplier to be changed.
     
  17. tamzzy

    Capodecina

    Joined: 26 May 2012

    Posts: 12,306

    probably have a duff cpu would be my honest guess