Nvidia 3DForce4-MX440 Series User Manual page 39

3D LC shutter glasses will not work unless nVIDIA's
stereoscopic effect is enabled.
Do not turn off and on your monitor when using stereo
mode. nVIDIA's stereo signal may be malfunction if monitor's
power is reset. APEC's LC shutter glasses will detect the
stereo signal and stop working automatically if the correct
stereo signal is not provided. It is necessary to reboot your
PC in order to make stereo available again if this situation
occurs.
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