Why some newer LCD panels have 120Hz refresh rate, and not 60Hz? How we can determine what is the most optimal resolution to use to display content on our LCD, does it depends of our CPU power or GPU power? What we get with that 120 Hz and even higher refresh rate frequencies?
120Hz panels can appear smoother, but most people will not notice a difference from 60Hz. They also have lower latency; this is preferred for gaming and especially VR where users want the minimum delay from control input or head movement until the display changes.
They're also used for shutter-glasses 3D; I have some nvidia kit that does this.
For TVs, it's of very questionable value. Remember that the source material is usually 30 frames per second, so all you'll see is more frames of the TV doing motion interpolation and de-interlacing.
Retail stores are pushing 120Hz and 240Hz LCD TVs as the 'fastest TVs' not because sales reps understand 120Hz and 240Hz technologies; most simply don't. Their real reason is that higher refresh rate LCD HDTVs are more expensive and often carry higher profit margins than 60Hz versions!