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Important reminder about voltages for overclockers

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PetrolHead View Drop Down
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    Posted: 09 Mar 2018 at 5:44am
Gamersnexus.net recently did a bit about safe voltages, which you can find here:

https://www.gamersnexus.net/guides/3251-raven-ridge-soc-voltage-guidelines-how-to-kill-cpu-with-safe-voltage

They're concentrating on Raven Ridge overclocking, but this should apply to pretty much all CPU overclocking: The voltage you set in BIOS or Ryzen Master may not be what the CPU actually receives. The voltage that is shown in HWMonitor and the like may also not be what the CPU actually receives. There are cases where the actual voltage is notably higher than the set or reported voltage, which means that if you are trying to stay just below what AMD declares it safe, you may in reality subjecting the CPU to voltages that will cause degradation over time.

The difference between the set and actual voltage will depend on the motherboard, possible LLC settings etc., so there's no easy way to adjust your settings correctly, if you are aiming for a "safe" value. Unfortunately it is not always clear to which voltages people are referring when talking about these "safe" voltages. Is AMD only talking about what is set in BIOS and if so, have they accounted for a worst case scenario between the set and measured voltage? What about if the safe voltage value is given by a motherboard manufacturer

In short, don't trust voltage values blindly, whether they are claimed safe voltages or voltages reported by software. If in doubt, play it safe. Also, if someone has done some measurements themselves, it would be interesting to know what sort of values ASRock's motherboards are posting. All I know is that according to HWMonitor my AB350M Pro4 uses a ~0.03V higher Vcore (under Prime95 testing) than what I've set in the BIOS. That alone is enough to encourage me to not use a "safe" value of 1.35V in the BIOS.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote scythefwd Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2018 at 11:16pm
HWMonitor agrees (max) with the voltage I assign in the bios, but shows that quite frequently I'm using .025 less than set (or an even larger delta)

Any suggestions on how to more accurately measure voltages?


I do also work up as low as possible.. 
OC - see if it runs stable, if not, add .025v, lather rinse repeat.  I find that 1.25 is sufficient for my 3900, and 1.35 is sufficient for my 4200.  I dont run at 42000.. I keep her at 3900
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PetrolHead Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr 2018 at 4:18pm
You'd probably need a multimeter to get more accurate information about the voltages. Using just software to measure the voltages, I don't think you can do much better than HWMonitor. Probably any other quality software will show you the same values as HWMonitor, but you can of course test different options and see what you get.

The voltage you set in BIOS is a target voltage and it's normal that the actual voltage varies based on CPU load, for example. On my system the reported voltage is in practice always higher than what I've set in the BIOS. This means I'm above my target Vcore even when Vdroop kicks in under heavy load. The downside is that the CPU is probably receiving more voltage than what it would need to be stable when it's not under heavy load.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Obligatory Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 2018 at 10:04am
Originally posted by PetrolHead PetrolHead wrote:

The voltage you set in BIOS is a target voltage and it's normal that the actual voltage varies based on CPU load, for example. On my system the reported voltage is in practice always higher than what I've set in the BIOS. This means I'm above my target Vcore even when Vdroop kicks in under heavy load. The downside is that the CPU is probably receiving more voltage than what it would need to be stable when it's not under heavy load.


I have the inverse issue:
-BIOS voltage is set to 1.375v for a 3800mhz clock
-HWMon/HWInfo report 1.337v while performing Prime95 tests

BUT, my 1700X will idle at the 1.375v... Even though I have Pstates set MUCH lower for idle conditions....

So - I guess I should go purchase some hardware to test my CPU voltage and continue refining my overclock voltage...? I feel like my situation makes zero sense... Over volting during load makes sense... Not overvolting during idle...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PetrolHead Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 2018 at 1:34pm
I don't use P-states myself, but I'd guess that's where the issue is. It could be that some program running in the background causes enough CPU load to prevent dropping to lower P-states. Otherwise those numbers seem normal. You've set 1.375V in BIOS and you're seeing 1.375V normally, then under heavy load Vdroop takes that voltage to 1.337V. I think this is pretty much what you should see without LLC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Obligatory Quote  Post ReplyReply Direct Link To This Post Posted: 02 May 2018 at 5:26am
You make good points.

However, I had LLC set to level 2 when I got those voltage numbers =(

So, stands to reason my load voltage should be closer to 1.375v with Vdroop, with those settings in bios.

Maybe I'll read through that GN article - maybe that'll shed some light on my issue.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote PetrolHead Quote  Post ReplyReply Direct Link To This Post Posted: 02 May 2018 at 4:11pm
Hmm. Maybe I was wrond and that's what you should expect with linear LLC that's not overly agressive. After all, the drop is not huge - at least on older systems the Vdroop could be over 0.1V without LLC. Have you checked what numbers you get with different LLC settings?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ALB92 Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2018 at 10:55am
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Originally posted by Obligatory Obligatory wrote:

You make good points.

However, I had LLC set to level 2 when I got those voltage numbers =(

So, stands to reason my load voltage should be closer to 1.375v with Vdroop, with those settings in bios.

Maybe I'll read through that GN article - maybe that'll shed some light on my issue.



As you can see on this vid矇o: https://m.youtube.com/watch?v=BLqqc9N8hOw
on some boards different levels of LLC have the same effect as LLC set to Auto so this might be the case here as well hence why you dont see much of an impact by setting your LLC to level 2 . You should try a higher setting and look if that changes anything .



To come back to the topic i myself try to OC my 1600 on an ab350-itx and it would be very interesting to know what is the real voltage for different settings . So the question is does someone here knows where to mesure VCore or and SoC voltage with a MM on AM4 motherboards ?

Edited by ALB92 - 11 May 2018 at 10:56am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ALB92 Quote  Post ReplyReply Direct Link To This Post Posted: 20 May 2018 at 10:01am
After some research i found the answer to my question : https://youtu.be/2DGDViPRh9k so i leave it here incase that can help someone .
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