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Around 2004, why did chipmakers shift from faster clocks toward multicore processors?

Higher clock speeds drove power use way up once Dennard scaling ended.

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  1. Higher clocks used far too much power ✔
  2. Software could not use speeds above 3 GHz
  3. Transistors stopped shrinking completely

Why: Dennard scaling meant smaller transistors used less power, so clocks could rise freely. When it ended around 2004, faster clocks meant much more power and heat. Designers put several slower cores on one chip instead.

Huh, didn't know that: Multiple cores can execute separate instruction streams at the same time, but one serial task cannot automatically use every core.

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Why did the CPU get more cores? It wanted to multitask without breaking a sweat.
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References

Answer: Higher clocks used far too much power. Dennard scaling meant smaller transistors used less power, so clocks could rise freely. When it ended around 2004, faster clocks meant much more power and heat. Designers put several slower cores on one chip instead.

  1. OpenStax Introduction to Computer Science 5.6: Processor Architectures openstax.org/books/introduction-computer-science/pages/5-6-processor-architectures
    Dennard scaling stopped and designers kept increasing the frequency of processors to make them faster. This led to a complete stall
    Checked 2026-10-10.

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