Newbie question about undervolting.

[jansimek]

Hello guys! so i've had my 9900k for over a month now and decided to undervolt. At stock settings with MCE off, the vcore under load is anywhere between 1.25-1.35v with occassional spikes up to 1.37. I did some digging and from what i understand, this is still completely fine and within specs, my temps are under control, too. However, i dont think this much voltage is necessary for 4,7ghz all core load, so i decided to undervolt. I have been playing with static vcore a couple weeks ago and was getting whea errors running aida64 up until i set the static vcore in bios to 1.190 so im thinking its safe to assume that my 9900k will need roughly 1.2V to do stock settings?

I dont want a static vcore though, so i did some more digging and found about a DVID option on my motherboard (Gigabyte z390 Aorus Master) and from what i understand, this setting should limit the maxium allowed vcore voltage supplied by the mobo while staying dynamic.

if i put a value of -0.150V in the DVID, that would mean the vcore limit would then be around 1.22v considering it creeps up to as high as 1.37 on auto vcore, right?

is this way of undervolting safe for long term use? i dont plan on overclocking right now, the processors performance is more than enough for me.

bios settings :

MCE : off
XMP 1 : ddr4 @2666 cl13 1.35v (creeps up to about 1.38 occassionaly which is fine i suppose)
Turbo Boost : enabled running at stock settings
Hyperthreading : enabled
Vcore : normal
DVID : -0.150v

 

[jansimek]

I would never use auto-vcore.

I didnt like the auto vcore either because it overvolts. Would you still consider normal vcore mode with undervolt via the DVID offset auto? i am really green when it comes to overclocking stuff.

Been running latest version of p95 small ffts on all 16 threads and the cpu sat between 1.104 - 1.116v at the all core 4,7 boost. Also tried running the same test on only 2 threads to get the cpu to the stock 5ghz (2core max) turbo, in that case it sits at 1.130 - 1.150

Would you consider running at stock turbo behavior at those voltages safe when 100% stable? i will definitely do some more prolonged testing. Is this a case of "if it works, it works?"

(temps are not an issue at all, but its nice to see a 10c improvement while keeping the same clocks and performance)

 

[jansimek]

At stock settings with MCE off, the vcore under load is anywhere between 1.25-1.35v with occassional spikes up to 1.37. I did some digging and from what i understand, this is still completely fine and within specs, my temps are under control, too. However, i dont think this much voltage is necessary for 4,7ghz all core load, so i decided to undervolt. I have been playing with static vcore a couple weeks ago and was getting whea errors running aida64 up until i set the static vcore in bios to 1.190 so im thinking its safe to assume that my 9900k will need roughly 1.2V to do stock settings?

if i put a value of -0.150V in the DVID, that would mean the vcore limit would then be around 1.22v considering it creeps up to as high as 1.37 on auto vcore, right?

First things first when using adaptive what is the stock voltage? You use the offset to + or - from that. I.e, I know my stock voltage on my 8600k is 1.165. Overclocking using static voltage I found that 1.34v was the voltage I needed to run stable @5Ghz. So, if I want to use adaptive I take 1.34v minus 1.165v gives me my offset of +0.175 This allows me to draw voltage anywhere from 1.165v up to 1.34v.

if i confirm that im stable at 1.2 manual vcore with other software such as what you recommended and newest prime 95, are my calculations correct? the board says stock is 1.2v in the vcore setting even when its on auto, but as i said it just creeps up as high as to 1.37

Thank you for the tips.

 

[jansimek]

are you taking your voltage reading from ‘vout’ using hwinfo? if not download hwinfo and use that reading to gauge the voltage.

vr vout peaks at 1.318 at auto vcore, 1.178 at a manual static vcore of 1.2 and at 1.180 when using the -0.150 dvid offset.

You get that from your Bios I.e, when you first booted it up, you was at 1.2v that is the default voltage for your cpu/board combo, not software.

at completely stock settings, when i boot into bios, it sits at 1.284 even though the auto vcore setting says 1.2v next to it.

 

[jansimek]

As to the stock voltage. Don't remember their being 2, unless your talking about the little slider box thingy. I just went of my Vcore in "Advanced Voltage Control" on an Aorus Gaming 5. So if that is showing 1.2v just go of that.

Keep dropping 0.005 and testing. It will take awhile but you will eventually be left with your lowest possible volt value for your cpu. Every cpu is different and this is the way if you want to reach your lowest stable volt on your cpu.

This is what i mean by the stock voltage its showing in the advanced voltage control : https://imgur.com/a/88iXWfM it says 1.2v next to the auto box where manual vcore is applied so i guess thats the same thing you just said? and the "slider box thingy" is where the current vcore is being reported (i think) thats where i saw the 1.284 in bios.


Guys, thank you very much for your time, i appreciate it! will report back when i figure this out

 

[jansimek]

Lastly remember that if you change your cpu clock ratio then you will have to tinker again. I saw you mentioned 4.7Ghz (47 cpu clock ratio) so you will be finding your lowest for that. If you decide you want to set your cpu clock ratio to say 48 for 4.8Ghz then you would do the same adding 0.005 volt until stable.

Yeah im undervolting for a 47x all core clock ratio which is stock max all core turbo, but the cpu will still be boosting up to 50x when only up to 2 cores are active, 49x up to 3 active cores, 48x up to 5 cores active and 47x from there

my last question : when i find the perfect lowest voltage for the all core 47x ratio, will it cause instability in instances where less cores are working, but are at a higher frequency? Im assuming that should be fine

 

[jansimek]

Thank you once again. Have a nice day!

 

[jansimek]

That is interesting, i either dont understand this at all (very likely) or my board doesnt behave like what Shamino described in that thread.

Anyway, been playing with the voltage a bit more and found out that it starts throwing whea errors and becomes unstable once i set the DVID to -0.165. It still seemed to run good at -0.160, but i set it to -0.155 just to give it a tiny bit more juice.

So right now, with basically everything in bios at stock except for a xmp profile, mce off, vcore set to "normal" and a DVID of -0.155 it passed this so far :


10 min p95(ver. 29.8) small fft all 16 threads

15min p95(ver. 29.8) blend test

10min aida64 system stability test (cpu, fpu, cache, memory)

3 cinebench r20 runs



Minimum Vcore recorded in HWINFO is 0.720 at idle and the max is 1.200v

VR VOUT shows values of 0.754 minimum and a peak of 1.184

The cpu package peaked at 80c, which is 15-20c less than i would have at "auto" vcore during a small fft run on a warm day.

I am happy with this and will monitor how it behaves in the next few days, hope i dont crash at idle or while web browsing.



Would there be a reason NOT TO keep it set like this if im 100% satisfied and it ends up working under all circumstances? (question for anyone experienced in the OC mastery who passes by and is willing to spend a minute )

 

[jansimek]

Okay, so after some more testing i'd love some opinions on whether or not i should consider this stable and stop tweaking.


Ended up manually changing the cpu clock ratio to 47.
MCE OFF
Turbo Boost OFF
XMP 1
and a DVID offset.

-0.160 error 5m into p95(version 29.8) small fft (worker error & stop +a whea error)

-0.155 error 12m into p95(version 29.8) small fft (worker error & stop +a whea error)

-0.150 error 30m min into p95(version 29.8) small fft (worker error & stop +a whea error)

-0.140 error 1h 20m into p95(version 29.8) small fft (this time only the worker stop & error happened with no whea log in windows. Sign of getting closer to 100% stable?)

-0.130 passed 3hours 48minutes p95(version 29.8) small fft with no errors. Cpu package max was 86c after almost 4 hours of what is the absolutely worst case scenario, if i understand the prime version differences right? im assuming that running the 26.6 non AVX version after this is pointless as that could probably go on forever.

Vcore under the newest p95 small fft test load im running is between 1.116 - 1.128 with the latest -0.130 DVID offset.



is this 100% stable?


Edit : i had no issues, errors, crashes or anything of that sort running games such as battlefield V and other stress tests such as Aida64, Realbench, Cinebench even at an offset of -0.150. It's just the P95 that kept producing errors up until i bumped it up to -0.130.

 

[jansimek]

Thank you for all the information and helping me understand Jason! i appreciate it.