In my experience, relying on distro-specific gui apps to alter settings leads to nothing but trouble. The best thing is just to stick with those provided by the xf86 package. Just run
as user, which starts a question/answer session. IT's important to remember that linux doesn't recognise monitor models in the same way windows does - if you set up your graphic card correctly and it is capable of driving the monitor then it doesn't matter. The only values you should need to enter for your monitor are the horizontal sync and vertical refresh rates, which should be in your manual.