If a GPU that is used for passthrough only (e.g. gaming VM) what are the GPU power saving features one can use on the host while the VM is not in use (power down) and the GPU is basically bound to VFIO drivers?
In other words, can the VFIO driver put the GPU into low P-States? Is this happening automatically or are special configurations required?
Does this depend on the GPU brand e.g. AMD vs nVIDIA or is the behavior the same for both brands?
Sorry if I made a mess here, I’m new to all this HW passthrough and all my current knowledge comes from watching videos and reading forums.
From my experience (in regards to fans spinning, noise, coil wine, heat) most GPU from AMD and NVIDIA most likely will throttle down, even if there is no drivers attached. If it is as low as in desktop use / stand-by I cannot say for certain, some of it will also depend on the cards firmware.
My current understanding is that modern GPUs can draw > 50W even in desktop mode while idling (or even more if multiple displays are attached).
This is what I would like to avoid. My host will run 7/24 and I would like to put the dGPU into a state where it draws basically no power when the gaming-VM is not running.
In my experience it is better to keep the VM running. In my case the WIndows driver in the guest is doing much better job keeping the card in low power state that the linux host.
The VM is configured to not go to sleep or turn off the monitor but it still uses ~30W less than if I simply shutdown the VM.