I have a GeForce 8400 GS video card, with the new 177.80 drivers both in Ubuntu (Intrepid Ibex) and in Mandriva (2009). However, I have a very strange problem that appears in Mandriva and doesn't appear in Ubuntu. When I run an OpenGL program in Mandriva, it's generally running smoothly, except that every about half a second it stops for a moment. It happened to me when trying glxgears, playing OpenArena, running Celestia...basically, in any OpenGL program I've tried. The only exception seem to be desktop effects such as Compiz or the KDE 4 effects, when they are enabled, they don't cause such problems. But when they are disabled, these problem still appears. I've tried using KDE and Gnome, and it's the same with both. When an OpenGL program stops for a moment, everything else seems to stop too...for example, when running glxgears and moving the mouse pointer over the desktop, the mouse pointer stops each time glxgears stops. Can someone help me fix this problem?
EDIT: Problem solved, the "nopat" kernel option made it work perfectly.