Question 8700k Vdroop Help

Jul 23, 2021
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Hey guys,

Generally new to overclocking with slightly above average knowledge on the topic.

My current issue right now is the slight vdroop i am currently experiencing and wondering if it is normal or maybe someway to regulate it. I am currently running a 4.7ghz overclock on my 8700k at 1.265v, temps are around 85c average after a 3 hours of prime95 version 26.6 running small ftt, Also did a blend test just for the heck of it and all in the clear. With hardwareid running i can tell that it normally sits at 1.264v under normal gaming/productivity use but then under maxed out 100% load it vdroops down to 1.248v and holds steady. When i run aida64 tho it bounces from 1.248v to 1.264v back and forth almost every 6-7 seconds which is also concerning since it doesn’t do that in prime95.

Some things to note:

-LLC is set to level 6 on my asus prime z370-a

-All intel power saving features are turned off

-MCE disabled

(Not currently home so this all that comes to mind, will update later tonight with more settings but generally speaking all bios options that should be off/on are so.)

Any help on this would lovely!

Please ask away if i forgot any key pieces of information for bios settings.
 

CompuTronix

Intel Master
Moderator
razzledazzler,

On behalf of Tom's Hardware Moderator Team, welcome aboard!

With Vcore set at 1.265 in BIOS, a Vdroop value in Windows from 1.264 to 1.248 is only 16 millivolts (0.016 volts), which is actually quite good. Even though Vcore settings in BIOS are typically commanded in 5mv increments, each 8mv step equals 1 bit, so 16mv equals 2 bits. In contrast, with 4th Generation processors such as the i7-4790K, the VRM was integrated into the Package ("Fully Integrated Voltage Regulator" or "FIVR"), so voltage regulation was very tight, and typically was within 1 bit, which is only 8mv. Essentially, what you set was what you get.

Voltage droop or voltage "sag" is normal and expected due to momentary "inrush current" which occurs whenever workload suddenly increases. However, although LLC is designed to compensate for Vdroop, the ideal setting will slightly undershoot (but not overshoot) your BIOS setting during the heaviest workloads, whereas excessive Vdroop can cause instabilities and BSODs.

For comparison:

Good - 8 or 16 mv
Fair - 24 or 32 mv
Poor - 40 or 48 mv
RMA - 56 or > mv

Moreover, Vcore is most likely to fluctuate with workloads which fluctuate.

“Stress” tests vary widely and can be characterized into two categories; stability tests which are fluctuating workloads, and thermal tests which are steady workloads. Prime95 Small FFTs (AVX disabled) is ideally suited for testing thermal performance, because it conforms to Intel's Datasheets as a steady 100% workload with steady Core temperatures. No other non-proprietary utility can so closely replicate Intel's thermal test workload.

Utilities that don't overload or underload your processor will give you a valid thermal baseline. Here’s a comparison of utilities grouped as thermal and stability tests according to % of TDP, averaged across six processor Generations at stock Intel settings rounded to the nearest 5%:



Although these tests range from 70% to 130% TDP workload, Windows Task Manager interprets every test as 100% CPU Utilization, which is processor resource activity, not actual %TDP workload. Core temperatures respond directly to Power consumption (Watts), which is driven by workload. Prime95 Small FFTs (AVX disabled) provides the correct workload for testing thermal performance. If Core temperatures don't exceed 80°C, your CPU should run the most demanding real-world workloads without overheating.

Although "Throttle" temperature for your 8700K is 100°C, the consensus among well informed and highly experienced reviewers, system builders and expert overclockers, is that it's prudent to observe a reasonable thermal margin below Throttle temperature for ultimate stability, performance and longevity. So regardless of environmental conditions, hardware configurations, software workloads or any other variables, Core temperatures above 85°C are not recommended.

Here's the nominal operating range for Core temperature:

Core temperatures below 80°C are ideal.


For everyone's benefit, we'll also point out that Core temperatures, as well as all computer temperatures, increase and decrease with ambient (room) temperature, for which the International Standard for "normal" is 22°C of 72°F. So for every degree above normal your ambient temperature is, so will be your Core temperatures.

Concerning Prime95, regardless of the version, Small FFTs is a steady-state 100% workload which has steady Power consumption (Watts) and steady Core temperatures. Although version 26.6 does not have AVX Instruction Sets, later versions such as 30.3 allow all AVX test selections to be disabled.



As per Intel’s Datasheets, TDP and Thermal Specifications are validated “without AVX.

Prime95 with AVX test selections enabled will impose a brutal and unrealistic 130% workload which can increase Core temperatures by up to 20°C. Therefore, version 26.6 or later versions with all AVX test selections disabled provide the correct workload for testing thermal performance when using the Small FFTs test, due to its steady-state 100% workload, which is also useful for observing Vdroop and Vcore stability.

As you have also noted, AIDA64 causes Vdroop fluctuations. However, to put it into perspective, let's keep in mind that testing thermal performance differs from testing stability; thus the term "System Stability Test" in AIDA64. When commenting about AIDA64, users seldom make any distinctions concerning which test selections they ran.

AIDA64 has 4 CPU related stress test selections (CPU, FPU, Cache, Memory) which have 15 possible combinations that yield 15 different workloads and 15 different Core temperatures. The individual FPU test is about 115% workload, the CPU/FPU combination is about 90%, all 4 tests combined is about 80% and the individual CPU test is only about 70%. All other AIDA64 test selections are fluctuating workloads which are suitable for stability testing, but not for thermal testing or analyzing Vdroop.

If you'd like to learn more, then just click on the link in my signature.

Once again, welcome aboard!

CT :sol:
 
Was not 4.7 GHz the standard 1 or 2 cores busy turbo boost for the 8700K? Not sure if tinkering w/ LLC settings will gain you much on relatively stock clock speeds, nor would I worry about voltage not staying constant / 5-10 mv higher as long as the CPU is stable)

(Why disable MCE at all? With it enabled, but still in Balanced Power Mode in power plans, you can boost to 4.7 GHz and maintain it on all cores under load, and yet idle down to 800-1200 MHz when loafing at the desktop and solitaire, etc)
 

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