After a default installation of opensuse, then installing the nVidia driver, and then enabling the screensavers, I find that the openGL screensavers do not run full screen, but instead run in a box in the top left corner (probably 1/4 screen), with the rest of the screen white.
works fine with the driver from the NVidia repo on my 7600GT.
Make sure the driver used in your xorg.conf is “nvidia”
Try running the installer from the NVidia site instead of the one from the repo. There have been reports it is working better in some cases.