Undervolting AMD RX cards on Linux

FydeFyde Member Posts: 8
I'm trying to undervolt different models of AMD RX GPUs on Ubuntu.
I did a lot of research and, as far I know, my two only options are:

- Using ohgodatool to change vddc index

For example ohgodatool -i 0 --core-state 7 --core-vddc-idx 6, but I don't really understand this.
I'm testing on a RX 470 Mining Edition and on state 6 I have -26. -26 what? 26mV less than the base value? -26%? And what's the base value?
Also, if I understand correctly, I can't choose an arbitrary number of mV.

- Editing the VBIOS

This gives me more control but it's a nightmare.
A few questions: When editing the VoltageObjectInfo portion of the bios, how do I choose the value in mV?
I watched a video that explains this, and they say that the hex value should increase by one for every 6.25mV increase, but again, what's the base value? 0?

A couple more questions:
How does ethOS do this? How can it apply an arbitrary number of mV?
Is there a way to know the current value in mV that the card is using? I didn't find any tools to do this.
Do I have any other option?

Any help is appreciated, thanks.


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