GPU Voltage Control Support Coming To AMDGPU Driver

[aufkrawall]

Starting with Kepler, they mostly locked the vcore for changes. At least you can undervolt Pascal on Windows to some extent with MSI Afterburner boost level curve editor. I guess that's not possible on Linux.
I once tried a custom fan curve on Linux via scripts that call nvidia-settings. Everything seemed to be looking good at first, but then I noticed by looking at Talos Principle fps counter that every time nvidia-setting is called, there is a nasty frametime spike caused by the overhead. Switching fan speed with amdgpu via sysfs doesn't seem to show such issues.
Typical Nvidia Linux "exists, but is not fun" case.

[TumultuousUnicorn]

AMDGPU + RadeonSI seems really exciting. I hope AMD Navi will be in better shape than Vega.

[donbastiano]

I'm not sure, is it a generic (and nice) thing as I think (say Polaris ) or just for Sea/Volcanic Islands?

[oooverclocker]

Wonderful. I was waiting for voltage control and I'm very happy that this will come soon.

[Soul_keeper]

This is excellent news. Especially for vega owners since AMD locked the firmware so we can't flash custom fw anymore.
I look forward to lowering the voltage/clock on the GPU/HBM to reduce heat/noise.

[LeJimster]

I really hope they bring in the ability to control voltages, especially undervolting, which is really important to us Vega users especially.

[oooverclocker]

Especially for vega owners since AMD locked the firmware so we can't flash custom fw anymore.

Hmmm well that‘s bad news to me. I wasn‘t aware that AMD locks bioses of GPUs on Linux at all.
Some cards come with power limits of something like 250 watts although the hardware can handle up to about 400 watts with a modified cooling solution. Hopefully the options will turn out satisfying in the end when bios modding is prevented. I hate unstable clock rates at high loads.

[Soul_keeper]

Hmmm well that‘s bad news to me. I wasn‘t aware that AMD locks bioses of GPUs on Linux at all.
Some cards come with power limits of something like 250 watts although the hardware can handle up to about 400 watts with a modified cooling solution. Hopefully the options will turn out satisfying in the end when bios modding is prevented. I hate unstable clock rates at high loads.

Yeah, the card won't post with a custom fw anymore.
But this patch is the first step in what would be the equivalent of windows "softmods", so we can potentially control all the same stuff once the system is booted.

[Soul_keeper]

I just tried the patch. It don't allow any voltages to be shown or changed. I guess it's just the creation of the pp_sclk_od/pp_mclk_od files containing 0 or 1 to enable this feature when it is added/supported at a future date.
unless i'm missing something ...

[Spazturtle]

AMDGPU + RadeonSI seems really exciting. I hope AMD Navi will be in better shape than Vega.

If you undervolt Vega to 0.9v then it drops from using 325W to 155W and gains 5-10% performance, and this is without changing the core clock or memory clock.

The issue with Vega seam to be that they have such low yields that they are using lower grade dies which would normally be binned and putting a higher voltage though them. This and the fact the HBM2 is below spec. The Vega specification says Vega should have a core frequency of 1900MHz and a HBM frequency of 1500MHz. The smaller Vega dies like the one used in the new Intel CPU are competitive wit NVIDIA GPUs of the same wattage, and that is with the lower performing HBM. The Vega refresh should hopefully fix the current issues with Vega and make it competitive with NVIDIA's 11XX series.