The power stays stuck like that because after your clock fails, the driver has to restart.
It almost never recovers properly and you get stuck in the P2 power state.
Get yourself the nvidia profile inspector. Then go here (forget the version number circled, just get the latest):
Set to Off, smack Apply changes a time or 2 and then reboot. That setting doesn't change without a reboot.
That will stop the card from going into a low power state. Once you're done with your clocks, turn it back on or the power saving features won't work properly when the GPU is idle.