500 MHz clock what does this mean?

Generally when talking about CPUs or Memory, or any chipset used in electronic devices, the clock refers to the speed of the chip. It is measured in frequency and MHz stands for Mega Hertz. 500 MHz would be very slow for a computer while it would be just fine for a cell phone. Most computers today are around 2.5 GHz to 4.0 GHz. It takes 1000 MHz to make 1 GHz.