Ryzen 7040U Undervolting

Anybody know if we’ll be able to undervolt the Ryzen CPUs, whether through BIOS or Ryzen Master? My biggest complaint about my Intel 11th was the way the fans would sometimes ramp up for no reason, and we were locked out of undervolting it.

Maybe it can be done with GitHub - DavidS95/Smokeless_UMAF

Linking these as well as they seem promising:

UXTU is Windows only currently.

RyzenAdj has an open issue for 7040 series support.

Also bumping this thread as some people have received their AMD! I’m looking forward to testing undervolting when I receive my mainboard.

BIOS level would be sweet, though.

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Reviews are saying fans are way lighter on the ryzen, so it may not be necessary


Definitely should just for the battery life improvements. Might also be able to eke out more performance.


The open issue is now closed, but it looks like undervolting is not supported by that project(?)

So, I haven’t seen fixed undervolting support yet, and I don’t know if it’s possible, but:

I can confirm that ryzenadj recognizes the 7840U on my system and I messed around with it a bit, but haven’t tested out the AMD “Curve Optimizer” feature (I plan to), which is kind of an undervolt, but not quite.

Here’s an explanation on Zen2, here’s @TheTRUEAsian’s experience on Windows with Curve Optimizer + the rest of that thread, and here’s my explanation on what it does, from research.

For Curve Optimizer on ryzenadj, it looks like it’s not documented in the readme currently, but if you run just ryzenadj without any parameters, it will list all the possible options including:

--set-coall=<u32>    All core Curve Optimiser
--set-coper=<u32>    Per core Curve Optimiser
--set-cogfx=<u32>    iGPU Curve Optimiser

The code is here, and it looks like All core Curve Optimiser support was added for Phoenix in this commit, and Per core Curve Optimiser and iGPU Curve Optimiser was added in this commit bundled with Hawk Point. So it looks like those options should be supported on this platform currently.

Also, there’s some great info on 7840 CPU Power efficiency testing that may help, and hey! The creator of that now closed issue happened to post on that thread and is on here — hi @GreyXor :slight_smile: wondering if you have any insight?


Hi @Michael_Wu , I haven’t had the chance to explore these features yet. However, they are on my to-do list, and I plan to conduct benchmarks to determine the most efficient, powerful and low energy setup by using each flag of ryzenadj, I already know that the conventional flags (stapm and tctl-temp) are working


Awesome, I’m really looking forward to your results!

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Has there been any development on this?

Currently looking towards seeing how close to the full performance of the 7840U i can get without making it extremely hot ( and thus having a hair-blower on my desk ), and with Smokeless_UMAF not showing negative offsets(but can increase current if desired), and ryzenadj’s curve optimizer’s setting remaining undocumented (even to this date), it really seems like it’s the end of the road for these lofty thoughts (given how unlikely it is for UV to be made available through a BIOS update, given it’s an U-Series chip).

While I’d love to undervolt the thing, the performance per watt is already pretty freaking high. You really gotta load it up to actually get hair blower mode and even then stapm will kneecap you after a bit. Now if only they could make the hardware decoder not use way too much power on linux XD.

If you just want lower temps, ptm is probably the lowest hanging fruit.

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I am running my 7840U at these RyzenAdj settings: --apu-skin-temp 60 --slow-limit 43000

This raises the second power boost stage up to 43 Watt (4.1 GHz) instead of the default 35 Watt. It will also “disable” the normal base clock speed (3.3 GHz) at 30 Watt , since the skin temperature is set to 43.5 °C by default and will be hit after some minutes of full load (all cores).

I have applied PTM to the CPU, my laptop is raised on a laptop stand to increase air flow. Skin temperature will raise up to 52°C with full load on all cores.