7/1/2023 0 Comments Wontube high speed![]() Intel was once planning to reach a 10-GHz processor, but that remains as out of reach today as it was ten years ago. Why did processor clock speed stop increasing? Will processor clock speed start increasing again, or has that time passed? Why CPU Clock Speed Isn’t Increasing: Heat and PowerĪs we know from Moore’s law, transistor size is shrinking on a regular basis. ![]() This means more transistors can be packed into a processor. Typically this means greater processing power. There’s also another factor at play, called Dennard scaling. This principle states that the power needed to run transistors in a particular unit volume stays constant even as the number of transistors increases. However, we’ve begun to encounter the limits of Dennard scaling, and some are worried that Moore’s law is slowing down. Transistors have become so small that Dennard scaling no longer holds. Transistors shrink, but the power required to run them increases. Thermal losses are also a major factor in chip design. Cramming billions of transistors on a chip and turning them on and off thousands of times per second creates a ton of heat. That heat is deadly to high-precision and high-speed silicon. That heat has to go somewhere, and proper cooling solutions and chip designs are required to maintain reasonable clock speeds. The more transistors are added, the more robust the cooling system must be to accommodate the increased heat. Increase in clock speeds also implies a voltage increase, which leads to a cubic increase in power consumption for the chip. So as clock speeds go up, more heat is generated, requiring more powerful cooling solutions. Running those transistors and increasing clock speeds requires more voltage, leading to dramatically greater power consumption. So as we try to increase clock speed, we find that heat and power consumption increase dramatically. Why CPU Clock Speed Isn’t Increasing: Transistor Troubles In the end, power requirements and heat production outpace clock speed increases. Transistor design and composition are also preventing the easy headline clock speeds we once saw. While transistors are reliably getting smaller (witness shrinking process sizes over time), they’re not operating more rapidly. Typically, transistors have gotten faster because their gates (the part that moves in response to current) have thinned out. Yet since Intel’s 45nm process, the transistor gate is approximately 0.9nm thick, or about the width of a single silicon atom.
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