The crystal clock is a crystal oscillator, the full name of the crystal oscillator.
Crystal oscillator is the most important part of the clock circuit, its main role is to provide the reference frequency to the various parts of the graphics card, network card, motherboard and other accessories, it is like a ruler, the working frequency is unstable will cause the related equipment to work frequency is unstable, naturally prone to problems. Another function of the crystal oscillator is to generate oscillating current in the circuit, sending out a clock signal.