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This question is simple to the Core (excuse the pun). CPU = Central Processing Unit (for computing)

Lots of people including myself say "My CPU is doing a lot of work."

But I do not think that is the case... In the same way that a highway carries cars, but the car's engine does the Work. I am not tryin to persuede the answer, maybe I am, but anyway this question does not seem to be answered.

I am interested in the actual technical answer. and some nice healthy debate maybe :)

Does a CPU do work? If not then what does?

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  • $\begingroup$ I believe there is work done when you look at the minimal work required to manipulate a piece of information. Obviously computers do a lot more work than this which is mostly wasted because we do not know of a better way. $\endgroup$
    – DKNguyen
    Commented Jan 7, 2022 at 0:15
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    $\begingroup$ Debate is not what happens on SE generally. It's a straight Q&A website - it's not a discussion forum. $\endgroup$ Commented Jan 7, 2022 at 0:29
  • $\begingroup$ It's a complicated question. Feynman gives some of the answer in this book. amazon.com/Feynman-Lectures-Computation-Frontiers-Physics/dp/… $\endgroup$
    – Dan
    Commented Jan 7, 2022 at 1:16
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    $\begingroup$ charge is moved across the CPU die like cars across the highway. the scale is different ofc, does that really meant work isn't being done though? $\endgroup$
    – antimony
    Commented Jan 7, 2022 at 1:37
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    $\begingroup$ IMO CPUs do work, to perform computation charge is moved across the CPU die by an electric field $W= Q\int_{a}^{b} E \cdot dr$ $\endgroup$
    – antimony
    Commented Jan 7, 2022 at 1:42

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If you're driving a car you are using up energy to do so, in the sense that you are burning calories to move your body to control the vehicle. But the gas burned in the engine is what moves the car. You use energy to control a device that will use a lot more energy.

A CPU is just many many electric circuits, inside of all of those circuits charge flows across potentials, hence power is dissipated. Your CPU consumes power, and then uses it up to generate $0$'s and $1$'s. But those "control signals" then go to other elements, like a monitor, memory, speakers, and those also consume power by virtue of charges flowing across potentials.

Thinking about it in terms of "work" can get tricky. If a ball is dropped, does the earth do work to accelerate it, or does the balls potential energy just become kinetic; both are identical statements but it is all about perspective. In a certain sense the entire computer is a closed system and all the work is done by the wall plug. In another sense your entire house is a closed system and the work is done by the generator. It makes much more sense to think of these things, weather it be a CPU, a driver, or a highway as systems transacting energy as opposed to doing work on each other.

Almost identical to the example of driving a car. The "control signals" you generate cause other elements to use a lot of energy

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  • $\begingroup$ Fantastic, that's where I went with it also. I landed on the same closed systems, all the way back to the water flowing over the dam. $\endgroup$ Commented Jan 7, 2022 at 5:34
  • $\begingroup$ You could even argue that the Code that the Application is written in, is doing the work, or the person whom wrote the code did the work to enable the computer to do the math. $\endgroup$ Commented Jan 7, 2022 at 5:42

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