# Clock speed

> How many times per second a processor ticks, measured in gigahertz (GHz).

- Level: Basic
- Topics: Hardware
- URL: https://tidbit.legios.com.ar/clock-speed/
- In Spanish: [Velocidad de reloj](https://tidbit.legios.com.ar/es/clock-speed/)

Inside every CPU there is a **clock**: a signal that pulses at a perfectly regular rhythm, and every part of the chip moves one step forward on each pulse. **Clock speed** is how fast that rhythm is. One hertz is one tick per second, so a CPU at 3 **GHz** (gigahertz) ticks three billion times every second. Typical desktop and laptop processors run at roughly 2 to 5 GHz.

A faster clock means more steps per second, but it is not the whole story. How much work a core gets done on each tick depends on its design, so a newer CPU at 3 GHz can easily beat an older one at 4 GHz. The number of cores matters too. Comparing GHz only makes sense between chips of the same family and generation.

Clock speeds climbed fast until the mid-2000s and then mostly stopped, at a few gigahertz. Each extra tick costs power, and power turns into heat; past a point the chip simply gets too hot to cool. The industry turned to more cores and smarter designs instead. Modern CPUs also change speed constantly: they slow down when idle to save battery, and briefly speed up (**boost** or **turbo**) when you need a burst, as long as they stay cool enough.

## An analogy

The drummer on a galley ship. Every beat, the rowers pull once. A faster drummer means more strokes per minute, but how far the boat moves also depends on how strong each rower is and how many there are.

## Keep in mind

- Clock speed is the number of ticks per second; 1 GHz is a billion ticks.
- Work per tick depends on the chip's design, so GHz alone does not rank CPUs.
- Speeds plateaued at a few GHz because heat grows with every extra tick.
- CPUs slow down when idle and boost briefly under load.

## Go deeper

- [Clock rate on Wikipedia](https://en.wikipedia.org/wiki/Clock_rate)
- [Hertz on Wikipedia](https://en.wikipedia.org/wiki/Hertz)

## Related terms

- [CPU](https://tidbit.legios.com.ar/cpu/): The chip that runs your programs, one instruction after another, very fast.
- [Chip](https://tidbit.legios.com.ar/semiconductor-chip/): A sliver of silicon carrying billions of tiny switches that compute and remember.
- [Cores and threads](https://tidbit.legios.com.ar/cpu-cores-and-threads/): Why a CPU is really several processors, and why it can juggle even more tasks.