Question Is there any way at all to undervolt EPYC CPUs (Zen2 in this case) ?

[MLG-443]

Hi, I went through a lot to get where I am right now with a...

- H11DSi (supermicro mobo)
- 2x AMD EPYC 7k62
- 16x 8GB of 2933MHz RAM
- Clear linux live server OS (43470)

...working great but I want to keep it short as much as possible. Is there any way at all I can undervolt them ? (NOT simply switch P-states - I want to keep perfs nearly the same and try dialing down the power consumption.)
It is a good performance v.s. consumption compromise to turn off core performance boost but I have found that any other toggle would improve the performance-per-watt but maybe I am using them wrong. Is there any more that I can do ? Hence, I thought of undervolting but since we're talking about server CPU... well, it doesn't look like the search engines have much to say about that so I am hoping you have something to suggest to me.

This first point is really about getting the best performance²/watt overall. Not just if it is possible to undervolt.

If this isn't the right place to ask for this, please tell me. There is an absolutely overwhelming plethora of forums about DIY computers and technical know-how on the matter, I don't know where to start. :-/

 

[TerryLaze]

Undervolting can result in some software not getting enough volts to function properly, do you really want that?!
Also these CPUs are already dialed as much as possible towards best performance per watt so even a small amount of undervolting would be able to cause issues.

 

[MLG-443]

Thanks but I am referring to cases where the applications are very much non-critical (like mining for example) where no bit error would spell disaster so I would like to experiment and try anyway please.

I am not asking whether I should undervolt my EPYC cpus, I'm asking if there is any way I *can*.

 

[COLGeek]

Googling on this topic suggests that very few (maybe a couple) Threadripper motherboards have settings to allow for this.

From a quick look through your mobo manual, yours does not seem to allow such changes.

www.supermicro.com/manuals/motherboard/EPYC7000/MNL-2027.pdf

Aside from disabling cores, and dropping energy consumption and heat generation, I don't see a lot of options for you.

 

[MLG-443]

Thanks, you do not have to go through the same manual I already plowed through multiple times. I am certainly not looking to disable cores or compromise the performance severely. Disabling core perf boost was worth it because the power saved was a much higher percentage than the performance loss so I was hoping some other method of performance-per-watt optimization existed somewhere.

And AFAIK, cTDP can only be dropped to 200 W at most which is higher than these CPUs power consumption without core perf boost.