Overclock NVIDIA GPU to achieve undervolting

Question

While undervolting a CPU is straightforward, undervolting the dGPU is a bit trickier.

You can't directly undervolt the dGPU, but what you can do is overclock the frequency which results in any given frequency running at a lower voltage, thus effectively undervolting.

I have read first about this in this comment. u/Jr712 then provided more details in a post How I stopped my XPS 15 7590 GPU from throttling.

As described in the post, on Windows this can be done with MSI Afterburner. I would like to ask those of you who are more knowledgeable for instructions how can this be done on Linux.

I have read about this in some places, but as I have never done this before, I am not certain I will get what I want.

Here are some sources I have looked at:

• How to overclock Nvidia graphics cards on Linux
  In the video, there is actually a slide bar where I could undervolt directly. Should I instead do that? (Although in the comments someone says that "Nvidia is not allowing voltage control on Linux for new gen cards")
• How can I overclock a graphics card from within Ubuntu?

I know that overclocking is controlled via Coolbits

And as pointed out in Enabling overclocking:

The Coolbits option can be easily controlled with the nvidia-xconfig, which manipulates the Xorg configuration files:

nvidia-xconfig --cool-bits=*value*

But the above links set different levels: 12 vs. 28.

Also, I'd like to learn more about:

• What are the risks? Especially for CUDA usage (e.g. wrong calculations)?

  I can read in Enabling overclocking:

  Warning: Overclocking might permanently damage your hardware. You have been warned.

  This leads me to the next question:

• What is the "safe" range for overclocking?

• If I overclock the dGPU, should I offset also the mem clock? By how much?

Solution

The procedure you are describing to enable the overclock is correct. Usually I prefer to directly edit the configuration file in the X11 folder but there should be no difference in the two methods. I suggest to edit the coolbits to the value of 28.

If you wish to undervolt your GPU it will be less stable at high clock rates. Only in some special cases an undervolt enables extra clock rate (e.g. when the voltage is too high and causes overheating). In your case If you want to undervolt you should not increase the clock rate, you should leave it as default or lower a little bit until the system is stable.

Keep in mind that not all Nvidia GPUs are able to change the voltage, especially notebook GPUs won't allow voltage tweaking.

If you want to stop throttling of the GPU you should lower the temperatures by ramping up the fans rpm and possibly allow an higher power usage if the option is enabled in the nvidia-settings menu.

The possible risks of overclocking are:

• System instability with sudden screen freezes and random reboots.
• Overheating of the components with the possibility to lower the life span. Modern GPUs have some "self protection" capabilities so you aren't likely to immediately ruin it. A higher GPU temp means also higher CPU temp if the case has no airflow.
• Overclocking leads to a higher power usage that could stress your power supply if you exceed the rated maximum power allowed.

For some simple testing +100 MHz on the Core clock and +300/500 MHz for the VRAM are a safe starting point.

Comments

[Sandu Ursu]

Thank you!! I can't get past the nvidia-xconfig step. In case you have any suggestions: nvidia-xconfig breaks boot But, also: in the post they talk about overclocking only at lower voltages: one only needs to ramp up the frequency of lower voltages, effectively undervolting the GPU as it is running at its higher frequencies with lower voltage. An image from the post actually shows the frequency/voltage curve being set as a horizontal line. Can I do this on Linux, i.e. overclock at different voltages differently?

[Sandu Ursu]

"possibly allow an higher power usage" - wouldn't this actually increase heat?

[Edo98]

Definitely yes, higher power usage leads to higher heat dissipation which means higher temperatures if the cooling cannot keep up