My Nvidia Quadro P400 gpu had this weird issue in my Unraid box, that it was stuck on P0 (P-States are power stages that the GPU uses to save power when idle. P0 is full power, whilst P8 is all idle.)

The fix I found is the command listed below. For me, it is a permanent fix persistent between reboots.

Input this command in Unraids terminal (accessible from the GUI).

nvidia --persistenced

Check that it worked by using this command and check the P value:

nvidia-smi

Refrences