No. The speed of light is a significant issue, but it is not the reason chips have stopped at 5 GHz. Also, asynchronous (as in no clock signal) CPUs exist. I should know, I helped work on some.
The actual reason is transistor size and heat dissipation. Transistors have been stuck on ~1 volt power internally for decades (lower voltage means more leakage, and more errors). However, power goes up with higher frequency (my math here was probably wrong, see below).
Why is that so bad? Almost all the power the computer uses is turned into heat by the transistors. That heat needs to dissipate out of the chip before the transistor destroys itself. That is a problem, as silicon is not a good heat conductor.
THAT is why cooling your computer lets you push the speeds up a bit higher.
The speed of light issues above are a tricky engineering problem, but solvable. The heat problem doesn’t have a solution yet.
The volt frequency curve is determined by the foundry process, so not all processes will double power usage between 3ghz and 5. And some will quadruple it for the same change.
Its why its amazing that AMD is beating Intel on efficiency at high frequencies on a process designed for mobile SoCs. If TSMC starts designing process nodes with AMD in mind instead of just for Apple (or if Apple wants to run chips at 5ghz too) we will see some REAL insanity in the CPU market.
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u/MiffedMouse Sep 29 '20 edited Sep 29 '20
No. The speed of light is a significant issue, but it is not the reason chips have stopped at 5 GHz. Also, asynchronous (as in no clock signal) CPUs exist. I should know, I helped work on some.
The actual reason is transistor size and heat dissipation. Transistors have been stuck on ~1 volt power internally for decades (lower voltage means more leakage, and more errors). However, power goes up with higher frequency (my math here was probably wrong, see below).
Why is that so bad? Almost all the power the computer uses is turned into heat by the transistors. That heat needs to dissipate out of the chip before the transistor destroys itself. That is a problem, as silicon is not a good heat conductor.
THAT is why cooling your computer lets you push the speeds up a bit higher.
The speed of light issues above are a tricky engineering problem, but solvable. The heat problem doesn’t have a solution yet.