Here is my previous rant on video tearing of GTX 650 card in linux
With default nouveau driver in Ubuntu videos teared badly. After installing proprietary nvidia driver videos teared badly.
I guess the reason of tearing is graphics card is way faster in delivering frames which monitor can't match to display. In technical terms it is called a sync issue or whatever. See Screen Tearing in Wikipedia to know more
You should be running proprietary nvidia driver in linux, nouveau won't help
It is simple fix asking the window manager to request fullscreen repainting whenever some repaint is required. With KDE 4.11 this option is there.
In Unity this is done as follows in screenshots
Install Compiz settings
sudo apt-get install compizconfig-settings-manager
Search Compiz in unity dash
Launch Compiz and select Utility --> Workarounds
Tick "Force fullscreen redraws (buffer swap) on repaint"
By default vsync is enabled in nvidia-settings, if not enable it
Now reboot and enjoy (hopefully it works for you like it did for me)