First of all this problem is only with KDE, no matter what distro.
Im configuring my displays with nvidia-settings. I set to both right Hz and resolution
But on second display allways there is some line that is separate moving objects, like when i move window arround the screen some like moving from buttom to top of the screen. Ths is very bad at movies
Before few minutes i made a photo with my DSLR on high speed when moving an object on second display:


Please help

We'll need the english version of the problem first ;-P

1st off, is this a visual or a functional thing, ie. is there a visual line (or maybe friction "tearing") when you move around things or is there some barrier when you move windows around? Is the "line" horizontal or vertical?
2nd: (esp. if this is not a visual thing) please provide the output of "xrandr -q" so that we get an idea of your actual screen setup.