why does CPUs/CPU cores seem to be capped at 3 – 4 Ghz since almost a decade?
In: 1368
In addition to what everyone else said, there are some fundamental physical limitations at play.
When you turn off voltage in an electrical wire, there’s still some remnant current flowing through it (imagine going in a car. When you hit the brakes, it will still be moving for a while). This current lasts for a couple hundred ps (picoseconds), so the maximum theoretical frequency of conventional electronics is around 7,5 GHz. So even if we could create small enough CPUs/GPUs, we simply can’t move the signal fast enough through the wires.
There are a few areas of modern physics that are trying to overcome the issue. Instead of using electricity, these methods use light to move information. The two most promising options now are plasmonics (you shine light onto a metal and the light travels along the metal’s surface) and magnonics (you shine light on a magnet, you locally change it’s polarity and this “polarity wave” travels through the material).
ELI5 analogy: electrical wires are like a garden hose. When you turn off the water, there’s still some water dripping from the hose. Plasmonics and magnonics are like throwing water balloons.
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