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Ryzen 3000 SMT Off voltage - can you go higher than 1.325v allcore due to less current?

 
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post #1 of 7 (permalink) Old 11-04-2019, 04:01 AM - Thread Starter
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Ryzen 3000 SMT Off voltage - can you go higher than 1.325v allcore due to less current?

Posted elsewhere without much luck-

Have been playing around a lot with a 3800x with a fixed 1.325v voltage under load

Noticed that with SMT On and running various benchmarks , CPU current is up to around 70A and temps in the low 70's however with SMT Off, CPU current maxes in the high 40's and temperatures in the low 60s. .

Would it be safe to surpass the recognized 1.325v all core limit due to CPU current & temps being less with SMT off?

As far as degradation goes my understanding is that a few factors are at play besides from just voltage- assuming with lower temps, current etc this may make a case for more voltage

I have only done some brief testing but my 3800x is stable at 4.5ghz all core OC with HT off, as well as 3733mhz memory. cpu: 1.375v, dram 1.49v, soc 1.125v

thanks in advance,
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post #2 of 7 (permalink) Old 11-04-2019, 06:08 AM
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I think you would be fine. But I base this on the fact that the stock vcore on my 3800x sits at 1.38v at 4.3ghz across all core load. If that's good enough for AMD it's good enough for me. I can get 4.5ghz pass repeatedly in CBR20 at 1.33v, but I hit that up to 1.37v for stability. Even at 1.37v we only see 65c in a mid 20's ambient on water so it actually runs half a degree cooler than stock. On the stock cooler I would probably try and stay a lot lower though.
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post #3 of 7 (permalink) Old 11-04-2019, 07:43 AM
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Yeah you probably can go a little higher than 1.325 with SMT disabled being that there would would more deadzones within the cpu for heat to escape to. How much higher you can go is just a guess though.
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post #4 of 7 (permalink) Old 11-04-2019, 03:56 PM - Thread Starter
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Quote: Originally Posted by Nathan Ketil View Post
I think you would be fine. But I base this on the fact that the stock vcore on my 3800x sits at 1.38v at 4.3ghz across all core load. If that's good enough for AMD it's good enough for me. I can get 4.5ghz pass repeatedly in CBR20 at 1.33v, but I hit that up to 1.37v for stability. Even at 1.37v we only see 65c in a mid 20's ambient on water so it actually runs half a degree cooler than stock. On the stock cooler I would probably try and stay a lot lower though.
Quote: Originally Posted by 2600ryzen View Post
Yeah you probably can go a little higher than 1.325 with SMT disabled being that there would would more deadzones within the cpu for heat to escape to. How much higher you can go is just a guess though.
Thanks-

Good point about temps being a important factor when raising voltage

System seems to be stable at 1.375v. Temps in Realbench stay in the low 60's, while gaming (primary use of my system) doesn't seem to break into 50 degs even with vsync off trying to push as many fps as possible. This is with a NH-D15

Assume I will be ok but if I happen to blow up my system, i'll update this thread

Cheers,
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post #5 of 7 (permalink) Old 11-04-2019, 06:55 PM
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Let the CPU itself tell you.
Set PBO scalar manually to 1x (100% reliability, as intended by AMD) and you'll see.
Naturally you need to maximise PPT, TDC and EDC to prevent the voltage be limited because of them.

As said several times before, aside of just the workload, the maximum safe voltage will vary between different silicon characteristics.
Meaning no two CPUs (even of the same SKU) will be perfectly identical in that regard.
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post #6 of 7 (permalink) Old 11-04-2019, 10:34 PM - Thread Starter
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Quote: Originally Posted by The Stilt View Post
Let the CPU itself tell you.
Set PBO scalar manually to 1x (100% reliability, as intended by AMD) and you'll see.
Naturally you need to maximise PPT, TDC and EDC to prevent the voltage be limited because of them.

As said several times before, aside of just the workload, the maximum safe voltage will vary between different silicon characteristics.
Meaning no two CPUs (even of the same SKU) will be perfectly identical in that regard.
Thanks a lot for the suggestion - I will try this after work and report back

cheers,
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post #7 of 7 (permalink) Old 11-05-2019, 03:25 AM - Thread Starter
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Quote: Originally Posted by The Stilt View Post
Let the CPU itself tell you.
Set PBO scalar manually to 1x (100% reliability, as intended by AMD) and you'll see.
Naturally you need to maximise PPT, TDC and EDC to prevent the voltage be limited because of them.

As said several times before, aside of just the workload, the maximum safe voltage will vary between different silicon characteristics.
Meaning no two CPUs (even of the same SKU) will be perfectly identical in that regard.
Interesting findings - Using the above, it looks like it hovers between 1.356v and 1.362v while running realbench with all auto/stock BIOS settings (smt off) .

Have now reduced my voltage from 1.375v to 1.362v , system is stable @ 4475/8core/ 3733mhz ram. 25mhz loss but at least I know the voltages are safe

Thanks again for the suggestion
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