CPU power consumed relates to information processed?

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Discussion Overview

The discussion explores the relationship between CPU power consumption and the information processed, particularly in the context of superconducting CPUs and the implications of Landauer's principle. Participants examine the factors contributing to power consumption in traditional and hypothetical superconducting CPUs, considering both theoretical and practical aspects.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that CPUs consume power due to the ohmic resistance of transistors, questioning whether a superconducting CPU could operate with almost zero power consumption.
  • Others reference Landauer's principle, suggesting that even with superconductivity, there may still be a non-negligible power consumption due to entropy changes associated with information processing.
  • One participant notes that CMOS devices have capacitance that must be charged and discharged during logic level changes, contributing to power consumption.
  • Another participant discusses the challenges of reducing supply voltages in chip design to increase speed without increasing energy dissipation, highlighting the trade-offs involved.
  • A later reply reiterates the idea that while superconductors could reduce ohmic losses, there are still inherent limitations in transistor behavior that lead to power consumption, particularly during state transitions.

Areas of Agreement / Disagreement

Participants express differing views on the implications of superconductivity for CPU power consumption, with some supporting the idea that Landauer's principle applies while others question the completeness of this perspective. The discussion remains unresolved regarding the extent to which power consumption can be minimized in superconducting CPUs.

Contextual Notes

Participants acknowledge limitations in their arguments, including assumptions about ideal transistor behavior and the practical challenges of achieving superconductivity in CPUs. The discussion also reflects the complexity of power consumption mechanisms in electronic devices.

Delta2
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As far as i know CPUs consume power because of the ohmic resistance of the transistors that they are built of(i hope i am not wrong on this).

But if we were able to build some sort of superconducting CPU with almost zero ohmic resistances, would it be able to operate and perform computations with almost zero power, or (and here comes the interesting part of my question) because there are computations and hence information transformed, the entropy of the CPU is changing hence there has to be some non neglible power consumed by the CPU(even if it was superconducting)?
 
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So, if the CPU has zero ohmic resistances the CPU can operate fully with really very small power consumed as dictated by the Landauer's Limit?

Why i do feel something is not right, i feel like we are getting something (information processed by the CPU) while offering nothing or almost nothing as Landauer's energy is really small even if information is allowed to be erased?
 
CMOS devices have capacitance (both the traces on the chip and the gate capacitance of FETs). This has to be charged and discharged when the logic level/voltage changes.
 
CWatters said:
CMOS devices have capacitance (both the traces on the chip and the gate capacitance of FETs). This has to be charged and discharged when the logic level/voltage changes.
In an attempt to increase speed without increasing the Energy dissipated per cycle, chip makers have been using lower and lower supply voltages (E = CV2/2). This, of course, brings in other problems due to the low signal levels.
 
Delta² said:
As far as i know CPUs consume power because of the ohmic resistance of the transistors that they are built of(i hope i am not wrong on this).

But if we were able to build some sort of superconducting CPU with almost zero ohmic resistances, would it be able to operate and perform computations with almost zero power, or (and here comes the interesting part of my question) because there are computations and hence information transformed, the entropy of the CPU is changing hence there has to be some non neglible power consumed by the CPU(even if it was superconducting)?

I think Landauer's given above is the applicable principal of information processing, but here are the particulars of why information as manipulated by transistors must draw non-zero power.

Electronic computers represent binary information by means of transistors in an "on" or "off" state, i.e. a switch. The on state is characterized by relatively low resistance, and indeed transistors are constantly improved by further lowering the "on" resistance. But the "off" state is defined by relatively high resistance, the as switches are, and the opposite of the point of superconductors. To prevent loss in the off state the resistance should be infinite, but it never quite is and so when "off" transistors "leak". They leak less and less apparently with each new development but it never completely goes away. Furthermore, even though the switching time between on and off has decreased by many, many orders of magnitude with ever-new semiconductor developments, that time remains, and will remain non-zero. It is during this time that some current flows through a middling resistance and creates ohmic losses. There are still more imperfections in the model of transistor as a perfect all-on/all-off switch.
 

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