Computer Clock - Clock (Rate|Speed) - Hz


CPU's are marching forward at some frequency called the clock rate.

It is also known as the clock speed.

The clock rate is the speed at which a microprocessor executes instructions.

Every computer contains an internal clock (a clock generator) that regulates the rate at which instructions are executed by sending a clock signal and synchronizes all the various computer components.

The CPU requires a fixed number of clock ticks to execute each instruction. The faster the clock, the more instructions the CPU can execute per second.

Clock speed is the biggest contributor to power. Chip manufactures (Intel, esp.) pushed clock speeds very hard in the 90s and early 2000s. Doubling the clock speed increases power by 2-8x. Clock speed scaling is essentially finished. What’s Next: Parallelism. This is all the rage right now (multi-processor).

A 100Mhz processor will receive 100,000,000 clock ticks every second.


CPU clock speeds are barely increasing (Moores law hits the roof),

Units (Mhz to ns)

  • Rate often measured in MHz = millions of cycles/second
  • Time often measured in ns (nanoseconds)

<MATH> \begin{array}{rl} {X} \mbox{ MHz } && = && \frac{\displaystyle 1000}{\displaystyle X} \mbox{ ns} \\ 500 \text{ MHz} && \approx && 2 \text{ ns clock} \end{array} </MATH>

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