Struggling to get 4.7 GHz OC on an i7-8700K

[kingmustard]

EDIT: Seems 1.40v is the sweet spot on my system. See below.

• Intel Core i7-8700K
• OcUK (generic) 240mm liquid cooler
• Corsair Vengeance LPX 16 GB DDR4-3000
• Gigabyte Z370XP SLI with F6 UEFI (XMP enabled in UEFI)
• EVGA SuperNova NEX750B PSU

5-minute stress tests were ran and monitored using:

• Prime95 v29.4 build 8 (February 2018)
• AIDA64 5.95.4500 (November 2017)
• Core Temp v1.11 (November 2017)

All UEFI settings on Auto apart from the following being disabled:

• Enhanced Multi-Core Performance
• Intel Speed Shift Technology
• CPU Enhanced Halt (C1E)
• C3 State Support
• C6/C7 State Support
• C8 State Support
• C10 State Support
• VT-d
• Internal graphics

 

• 4.7 GHz @ 1.28v
  • Prime95 - Instant BSOD
  • AIDA64 - All cores 100% for full duration of 5m test, Package 104w, IA Cores 92w
• 4.7 GHz @ 1.30v
  • Prime95 - Only four cores at 100% from start of test, so cancelled the test
  • AIDA64 - All cores 100% for full duration of 5m test, Package 105w, IA Cores 93w
• 4.7 GHz @ 1.32v
  • Prime95 - Only five cores at 100% from start of test, so cancelled the test
  • AIDA64 - All cores 100% for full duration of 5m = test, Package 108w, IA Cores 95w
• 4.7 GHz @ 1.34v
  • Prime95 - All cores at 100% for 45s, then down to five, so cancelled the test
  • AIDA64 - All cores 100% for full duration of 5m test, Package 110w, IA Cores 98w
• 4.7 GHz @ 1.36v
  • Prime95 - Only four cores at 100% from start of test, so cancelled the test
  • AIDA64 - All cores 100% for full duration of 5m test, Package 113w, IA Cores 101w
• 4.7 GHz @ 1.38v
  • Prime95 - Only five cores at 100% from start of test, so cancelled the test
  • AIDA64 - All cores 100% for full duration of 5m test, Package 115w, IA Cores 102w
• 4.7 GHz @ 1.40v
  • Prime95 - All cores 100% for full duration of 2x 5m tests, Package 157w, IA Cores 146w
  • AIDA64 - All cores 100% for full duration of 5m test, Package 115w, IA Cores 102w

 

• 4.8 GHz @ 1.40v
  • Prime95 - Only three cores at 100% from start of test, so cancelled the test
• 4.8 GHz @ 1.42v
  • Prime95 - All cores at 100% for 1m 45s, then down to five, so cancelled the test
• 4.8 GHz @ 1.44v
  • Prime95 - All cores 100% for full duration of 5m test, Package 171w, IA Cores 160w but thermals were too high (85-90C)

[Crunchy Dragon]

1 minute ago, kingmustard said:

Should I go higher than 1.35v, or is that too high?

That wouldn't be considered "too high", the chip can take up to 1.5v

 

I would bump voltage up to 1.4v in slow increments of maybe 0.10v

[Yoola]

I wouldn't push voltages too far if it's not delidded. 

Once delidded, you're ok to go basically as far as temperatures reach you. 

[kingmustard]

Just now, Yoola said:

I wouldn't push voltages too far if it's not delidded. 

Once delidded, you're ok to go basically as far as temperatures reach you. 

What would you consider too far?

[Minotaur10]

You might get better stability with VCCIO 1.05V, C-state to high/higher, core current capability at 120%. I've managed to get a 4.8GHz on an ASUS Z370-P at 1.28V with these settings.

[GER_T4IGA]

5 minutes ago, kingmustard said:

What would you consider too far?

Depends on how long you want to run the chip. Most people consider 80 under load to be max for daily but from intel spec you could also run 95 ... but I doubt that it will last more than 3 years under daily use with such temps. Many high end laptops run at those temps but that is not a good thing by any means. I would keep it under 80 personally.

[Yoola]

8 minutes ago, kingmustard said:

What would you consider too far?

I'd say 1.4 for daily use. But that's again considering the temps are ok. What kind of temperatures are you getting now on this 240mm AIO?

[Ebony Falcon]

Follow the debour video on youtube, but 4.7 not 5ghz and see how that goes

if not rma that shit bro

[Ebony Falcon]

Can u try another stres test like Aida 64

prime can be aids 

[DarkSmith2]

4 hours ago, kingmustard said:

Gigabyte Z370XP SLI

This is your problem.

[aezakmi]

there are other tests that are more realistic, imho prime95 is crap

 

occt, aida, sandra, cpuburner if you want to check only temps

[kingmustard]

Looks like 1.40v is my sweet spot (see original post).

[DarkSmith2]

51 minutes ago, kingmustard said:

Looks like 1.40v is my sweet spot (see original post).

yea its because of the power delivery of your cheapo mainboard, with a good board your CPU would be able to pull 200-220w @1,40v Vcore.

[kingmustard]

Added 4.8 GHz tests. Unsuccessful.

[porina]

If you're happy that 4.7 is P95 stable (10 minutes isn't enough) you can try pushing further clock with AVX offset. This is how much clock multiplier is reduced when running software like Prime95. Other software could run further. So you could set 4.8 and AVX offset of 1, so that other software will run 4.8, P95 and similar at 4.7 still. Beware other software may trigger the offset, if they use AVX also. Cinebench R15 is a starting point to find non-AVX stability.

 

If you see any overclocks at 5 GHz+ without sub ambient cooling, that almost certainly is NOT running full fat P95. Some OC'ers run an old version that is weak like skimmed milk.

 

I don't have notes on me, from memory my 8350k does 5.0 at least bench stable but I think I've had to use AVX offset of 3.

[Kenrou]

See list below i did in OC.com and see the level of AVX you need, obviously the lower the setting the lower the heat you will produce.

 

26.6 = SSE = gaming, office work
27.7 = SSE/AVX = x264 encoding, image editing, heavy multitasking
28.5+ = SSE/AVX/AVX2/FMA3 = x265 encoding, folding, important work, ~100% stability

 

You can also add command lines to "local.txt" in Prime95 directory to simulate older versions:

 

CpuSupportsAVX=0
CpuSupportsAVX2=0
CpuSupportsFMA3=0

[tomoki]

What are all your settings?? 

I just finished overclocking my new 8700k @5.0GHz. It's set at adaptive 1.34V +0.02V offset. AVX at 3 and my temps at max (used Prime95) is having one core reach 77C. LLC level 5.

 

I'm using an Asus Prime Z370-A with a Dark Rock Pro 3. I haven't delidded yet. 

 

I haven't tested without AVX just yet. My previous overclocks didn't last more than 2 minutes in Prime95 but this one goes way beyond that so...