Help with (unsupported?) video card, refresh rate
 

The card is a GeForce FX 5200 (256 megs)

here's the /sbin/lspci info that relates to the video card:

0000:01:00.0 VGA compatible controller: nVidia Corporation: Unknown device 0326 (rev a1)

The card works, I can see videos and crap fine, but the screen has a visibly flickering refresh rate, at 100 Hz (the default, it won't go higher)

Any idea what's wrong? Why the refresh rate looks like this? (100 Hz works fine in Windows XP)

Are you using the official drivers from nvidia.com? If not, try them.