8700k seems stable at 5GHz and 1.275v with H115i cooler. Keep trying to lower volts?

[Amin Sabet]

Hi all, I am a beginner at CPU overclocking. I'm using a non-delidded 8700k with a Corsair H115i cooler

I started trying at 5GHz and 1.35v, but CPU temps were approaching 100 degrees under load. I tried 1.3v, than 1.275v, and it still seems stable.

At 1.275v and 5GHz, I can run RealBench 2.56 stress test with memory set to "Up to 16GB RAM" for 4 hours without going over 90 degrees or having any apparent instability. Based on my searching the forums, this seems to be a good result for this CPU.

Should I keep trying to lower the volts, or just be happy with what I got? I figure that if I go with the lowest volts that can "pass" RealBench, it might not be enough for real life tasks. And a max of 90 degrees should be fine, right?

 

[jojesa]

It looks like you got a gem. You should be happy.
But, I would go as low as possible while the system remains stable.
I have built three 8700k systems and have not been able to go lower than 1.32v @ 5GHz stable.

 

[zebarjadi.raouf]

Should I keep trying to lower the volts, or just be happy with what I got?

You can go lower if you want or if you have heat issues.

I figure that if I go with the lowest volts that can "pass" RealBench, it might not be enough for real life tasks.

That's true. You might crash while doing something else. Mine passed Prime95 + AIDA64 (12 hours each), crashed while shutting down.

And a max of 90 degrees should be fine, right?

Max 90c is for stress testing. 80c is the max for daily usage.
------------
BTW, did you enable LLC (Load Line Calibration)? It can help when lowering voltage by preventing voltage drop. Level 4/50% should be a good start.

 

[bmockeg]

If it passes realbench, it will be fine for every day tasks.

 

[Amin Sabet]

Thanks, everyone!

BTW, did you enable LLC (Load Line Calibration)? It can help when lowering voltage by preventing voltage drop. Level 4/50% should be a good start.

I'll give it a try, thanks!

 

[4Ryan6]

@Amin Sabet

Amin, it would help if you listed your full specs.

 

[Amin Sabet]

@Amin Sabet

Amin, it would help if you listed your full specs.

Here are my full specs:

• 
  Case: Fractal Define R6
  CPU cooler: Corsair H115i Pro
  Power supply: Corsair HX850i
  OS: Windows 10 Pro 64-bit
  CPU: i7-8700k
  Boot drive: Samsung 970 Evo 1TB NVMe M.2 SSD
  RAM: G.Skill Ripjaws V 32GB 2 x 16GB DDR4-3200
  Motherboard: ASUS ROG STRIX Z370-E
  GPU: NVIDIA GeForce GTX 1070 Founders Edition
  Thermal compound: Arctic Silver 5

And here are my BIOS settings changes:

• 
  AI Overclock Tuner: Manual
  ASUS MultiCore Enhancement: Disabled
  AVX Instruction Core Ratio Negative Offset: 2
  CPU Core Ratio [Per Core]: Sync All Cores
  1-6 Core Ratio Limit: 50
  CPU SVID Support: Disabled
  CPU Core/Cache Current Limit Max: 255.50
  BCLK Aware Adaptive Voltage: Disabled
  CPU Core/Cache Voltage: Manual Mode
  CPU Core Voltage Override: 1.275
  CPU Load-line Calibration: Level 6
  Intel SpeedStep: Disabled
  DRAM Voltage: 1.3530
  DRAM Frequency: DDR4-3200MHz
  DRAM CAS# Latency: 16
  DRAM RAS# to CAS# Delay: 18
  DRAM RAS# ACT Time: 38
  DRAM Command Rate: 1N

System seems very stable in both stress tests and regular use .

 

[zebarjadi.raouf]

Here are my full specs:

Case: Fractal Define R6
CPU cooler: Corsair H115i Pro
Power supply: Corsair HX850i
OS: Windows 10 Pro 64-bit
CPU: i7-8700k
Boot drive: Samsung 970 Evo 1TB NVMe M.2 SSD
RAM: G.Skill Ripjaws V 32GB 2 x 16GB DDR4-3200
Motherboard: ASUS ROG STRIX Z370-E
GPU: NVIDIA GeForce GTX 1070 Founders Edition
Thermal compound: Arctic Silver 5

Nice build.

System seems very stable in both stress tests and regular use .

Use for a week, if nothing happens, you could try lowering voltage. But good enough in my opinion. Most people reach 5GHz with 1.30v-1.35v.

 

[Amin Sabet]

Nice build.

Thanks!

Use for a week, if nothing happens, you could try lowering voltage. But good enough in my opinion. Most people reach 5GHz with 1.30v-1.35v.

That sounds like a good plan. Thanks, again!

 

[vMax]

That is simply a great CPU, mine just couldn't get anywhere near that at 5GHz...I get 4.9 at 1.27v but 5GHz just needs way too much..be happy!

 

[Amin Sabet]

Thank you, I'm very pleased with it!