I have noticed that D-Nice and others seem to suggest turning the power save mode to off. I was wondering why? Will using one of these settings affect the picture quality?

Thanks in advance.

powersave off is the normal setting for the full performance of the panel.
turning it to 1 or 2 will lower the brightness a little and also limit the peak output it can achieve. but most people do not even notice. and some have had their panel calibrated with it on powersave 2. plus it may help if you have a buzz issue with your panel.