NVDEC forces GPU into P2 CUDA state -> much higher power consumption than with VDPAU

With VDPAU, the GPU is allowed to reduce clocks below P2 CUDA and P0 states. This is not the case with NVDEC, it forces the card into P2 CUDA state which totally prevents any downclocking below high baseclock (e.g. ~1.5GHz for a GTX 1070).
Thus power consumption with NVDEC is much higher than with VDPAU.

→ Please implement power savings when only NVDEC is used and not any other CUDA activity is going on!

Now in 2022, this issue is still present in both Linux NVIDIA 515.48.07 driver and Windows NVIDIA 512.95 driver.
There is no way to disable this driver behavior.

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Not true. Just checked mpv.com --vf=format=gamma=pq:primaries=bt.2020:colorlevels=full --target-colorspace-hint=yes -hwdec=nvdec --gpu-api=vulkan -vo=gpu-next Z:\Raya.and.the.Last.Dragon.2021.2160p.DSNP.WEB-DL.DDP.5.1.Atmos.DoVi.by.DVT.mp4

After initial P2 in seconds it get to P5 and if you open some other app to P3 (in nvidia-smi.exe)

| 41% 44C P5 37W / 260W | 2403MiB / 11264MiB | 14% Default |

So this is HEVC with Dolby Vision colorspace that is decoded using Vulkan shader.