Wait... is this thread real?
I don't care who you are... there is no way you can see flicker at 200+ Hz.....
People who claim that they can see high frequency flicker are probably just seeing low frequency flicker caused by Beat Frequency Oscillation.
Place a light source that is flickering at say 250Hz, next to another light source flickering at 260Hz. And you will then get a 10Hz flicker.