Ebrahim Nelson Ceesay

Hello, i was recently setting my main Display (Asus vg248qe) to 25hz because i got excelent smoothness with that. (it really works amazing even on my 5 year old machine) For normal use of my Laptop i usually reset the frequency back to 60hz. I use Nvidia Control Panel to do that. I now noticed that my screen is much darker on 25hz then it use to be on 60hz. I was wondering how to cerrect it? Should i just adjust the brightness in the Nvidia Control Panel or is there another reason for that? I was searching a bit arround google but unfortunatly found no answer to that .