What connection to GPU are you using?
edit: yea as #1 said. .probably because you use HDMI.. you have to use dual-link DVI cable
You changing it in nvidia control panel? If not, that's where you need to go
I had the same issue a while ago, 144Hz setting won't save. It was vibranceGUI.exe switching it back to 60Hz everytime just delete vibranceGUI then reboot, switch to 144Hz and it should work. You can install vibranceGUI again when 144Hz is saved.
maybe you have regular DVI cable and not dual link
nie wiem czy ten problem masz wszedzie czy tylko w cs'ie ale jak w cs'ie to w opcjach uruchamiania wpisz -freq 144
sell your pc and every problem in your life will be fixed
I was with the same problem just preinstall the windows and you are rdy
I use DP (Display Port) and don't have that problem