I might be missing something here, but I've never been able to use nvidia-setttings in any distribution (KDE). I just start PCC, go to hardware, then Configure Video Card, select the proper video card, that selection seems to start the script to ask you: Do you want to use the Proprietary Driver?, select your monitor, resolution (that you should know for your flat panel or monitor), select your options, reboot and xorg.conf is written for you. Then you restart your computer and your settings have been applied and your off and running.That's what is so great, it's all done for you and you can add some lines shown in the Nvida appendix if you want. Most settings don't apply to newer Nvidia Cards, but I set it up once with a 480GTX, just to be able to control the speed of the cooling fan on the video card and it worked.
You don't give your model of your card so I don't know if your card is older or newer, but that's one reason I've stuck with Nvidia cards because their Proprietary Drivers work well, even though there is a rift between Linus and Nvidia for not giving them more source to work with to develop the Open Source drivers.