There's is not really a Nyquist for the eye, the eye is "analog" - for monitors, and televisions you are looking for the refresh rate that the eye will not perceive the flicker - or strobbing of a digital image. The eye can pick up individual images at pretty high speed. That will depend on what will be on the monitor - High quality TV are at 240fps - but then it will still depend on the content and does it introduce distortion. Keep in mind that most video content is between 14 and 60 FPS