On some graphics cards, clocks may not drop to idle rates.

On some graphics cards, clocks may not drop to idle rates when the monitor refresh rate is set to 120Hz.

The graphics card has multiple clock rates available based on the load presented to the card.  When refreshing the screen at 120Hz, the clock rate may not drop to idle rates in order to avoid screen flashing or flickering.

These clock rates are normal and will not hurt the card, system or monitor in any way.  However, setting the screen refresh rate to a value below 120Hz will allow the card to drop to the lower idle rates.