Msi gtx 970

Solution
If you go into the Nvidia GeForce Experience application, you can use the LED Visualizer to decrease the brightness to zero (effectively turned off). That's how I have mine set. Sometimes you need to repeat after PC reboots.

EDIT: Checking the visualizer reveals that there is actually an option to turn LED effects off altogether.
If you go into the Nvidia GeForce Experience application, you can use the LED Visualizer to decrease the brightness to zero (effectively turned off). That's how I have mine set. Sometimes you need to repeat after PC reboots.

EDIT: Checking the visualizer reveals that there is actually an option to turn LED effects off altogether.
 
Solution