Question about CPU voltage and overclocking

[Fuelrod]

I don’t overclock a lot so pardon if this is a stupid question. I have a 6700K and when it is not overclocked and sitting idle the voltage on the CPU drops well below 1v. Once a load is placed on the CPU the voltage jumps to 1.28v to 1.29v. If I increase the voltage in the bios to overclock the CPU to let’s say 1.36v, then the voltage is usually around to 1.35v regardless of whether the CPU is idle or under load. Is there a setting in the bios when overclocking than would allow the voltage to remain low when idle then jump up to the OC voltage I specify only when under load? It seems like a waste and potentially harmful to keep the CPU at the higher voltage when it is idle and not doing anything.

 

[coercitiv]

It seems like a waste and potentially harmful to keep the CPU at the higher voltage when it is idle and not doing anything.

It's not harmful.

• If you want to optimize power draw you can read about what Adaptive or Offset CPU voltage modes can do, as opposed to the Manual static mode you are using right now. Both of them will allow you to lower CPU voltage when frequency goes down.
  
• One other way to obtain more or less the same power saving result is to check and enable C7 or C8 sleep state for the CPU. This way cores will be effectively shut down when idle, allowing you to leave frequency/voltage settings as they are right now.

 

[LTC8K6]

Yes, it's because you manually set the voltage to a fixed number instead of using say a +.10 volt offset.

 

[VirtualLarry]

Good question. Usually, when overclocking (Skylake), your board will give you a choice of manual/fixed, and offset, voltage settings. You would want to use "offset".

I use "Fixed" for my BCLK OC, because power-management / power-saving steps are disabled due to BCLK OC.

 

[BonzaiDuck]

My colleagues here are closer to "major league geek" and I could still be in the "minors."

But here are some tips. First, distinguish between unloaded Turbo voltage and loaded VCORE. Be familiar with the difference between VID and VCORE. You'll especially want to monitor VCORE and pay attention to it as much as anything.

Use "Adaptive" mode settings, and either leave Offset on "Auto" or set it to the nominal one notch above zero. For 4.5 Ghz, start testing your overclock with 1.280V showing as "load VCORE." You'll start by setting the adaptive voltage "for Turbo" somewhere near that number, and find that the loaded VCORE is still a tad higher than you wanted to set.

You should probably set Load-Line-Calibration to a notch above the middle setting; on my ASUS board, it is "Level 5." It is possible to determine approximately what "Auto" gives you at stock speed and voltage by watching the actual VCORE in a comparison to what the lowest setting provides -- assuming you don't crash your system at stock settings just to find out. But the ASUS Z170's seem to default to Level 5 with an "Auto" LLC setting.

Leave EIST and the other power-saving features "enabled" or "Auto." For 4.6Ghz, start tuning either up or down from a load VCORE of 1.344V. Again, what you set in the BIOS menu will be trial and error against what a windows session will show as load VCORE during a brief stress-test. Again, my best guess is that an ample but reasonable load VCORE might be just a couple-notches above 1.344V -- more or less. At 4.7, figure the load VCORE at a sensible LLC setting should bottom out between 1.39 and 1.408V.

Temperature may limit your overclock, so you might be most comfortable if that's the case with 4.5 Ghz. Personally, I think you're "at the end of your string" if the Peak Package temperature during stress-testing goes above 80C. A 212 EVO cooler might put you "right there" at 4.5 Ghz. Even if the chip is safe at higher temperatures, the overclock is less likely to be stable because of temperature-generated electrical noise.

If you get this right, you'll see the VCORE drop to between 0.7 and 0.8V during idle under EIST, and rise to the range between load and idle Turbo with a stable overclock. The difference between the loaded and idle values is probably an indication of the "vDROOP" remaining with LLC in effect. You always want to keep a few millivolts of droop.