LCD monitors do NOT flicker like CRT monitors.
CRT monitors use an electron beam that scans the inside of the picture tube. On the inside face of the tube, red, green and blue phosphor dots emit light when struck by the electron beam. Once lit, the luminance of the phosphor starts to degrade until the beam comes back around to refresh it. This is known as the refresh rate.
LCD monitors use a matrix of cells 1024 x 768 for a 15?, 1280 x 1024 for an 17, 18 and most 19?. LCD monitors use a back light to create the luminance and is always on. Each cell has three transistors that let current flow through liquid crystal. One for red, one for blue and one for green. When the transistor is on, it allows light to pass. Think of it as a light valve. Colors are produced on LCD monitors using polarized filters. When the transistor turns on, it stays on, for the full cycle or refresh time, thus the amount of light output stays constant. No flicker no matter what the refresh rates.