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Why Do Computers Use So Much Energy?

blogs.scientificamerican.com

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Re: Why Do Computers Use So Much Energy?

#21

Post by village-idiot »

supernovae wrote: post #7
pizzakiller85 wrote: post #2

What i don't understand is how a phone can be so powerful with so little watt usage. especially compared to a PC

There are a lot of efficient PC's available. My HTPC sleeps when not playing and when streaming 1080p/4k videos only uses about 25 watts... which isn't bad considering its streaming from a NAS with plex through to an Xbox One. Phones, on the other hand, are highly specialized - PC's are general purpose. Trade off is often power requirements and performance. My 8 core 16 thread Ryzen Gaming PC smokes anything my phone…

It’s also a consequence of constraints. There has not been a pressure to make desktops more energy efficient, since they’re attached to a permanent source of incredibly cheap power. Even laptops spend a large portion of their time wired in.

Phones on the other hand are rarely plugged in, and consumers clearly demand more battery life. This has led to resources being poured into cell phone battery capacity and into efficiencies in power usage.

Re: Why Do Computers Use So Much Energy?

#22

Post by gvb »

pizzakiller85 wrote: post #2

What i don't understand is how a phone can be so powerful with so little watt usage. especially compared to a PC

1) Your phone is mostly sleeping (extremely low power state). Your laptop also uses very little power when sleeping. That is why your laptop can sleep for a week++ but can only run for 3-8 hours.

2) Your phone is not nearly as powerful as your laptop despite similar specifications of the CPU speeds. Pretty much everything other than the base CPU clock rate is much, much slower. In addition, your phone CPU down-clocks itself due to thermal limitations where your laptop has a fan and much better heat dissipation capabilities. As a result, it is almost never running at the maximum rated clock speed.

On a YouTube talk I watched (skewering web site speeds and JavaScript overloads), the speaker's iPhone, with CPU specs similar to his laptop, was 25 times slower than his laptop when rendering a (JavaScript heavy) benchmark page.

Re: Why Do Computers Use So Much Energy?

#23

Post by ashelmire »

gameswithgo wrote: post #20
lucideer wrote: post #12

> Precise estimates vary, but currently about 5 percent of all energy consumption in the U.S. goes just to running computers 30% goes on transport. > the human brain is a computer. This particular computer uses some 10–20 percent of all the calories that a human consumes So society's computer uses 5 percent and our own, evolved over millions of years, uses up to 20. I'm not saying computers can't or shouldn't be made…

You could probably cut that consumption in half if people stopped using interpreted languages in production, quit telling curious young programmers that early optimization is evil or that memory is an implementation detail, etc. etc. The computer is very efficient, electrical engineers toil and sweat a great deal to make them so. Then we build things with Ruby and Python and make things 2 orders of magnitude less eff…

> no good reason

If it takes a developer hours to build something that would otherwise take days, that's a very good reason. Processing power and energy are a tiny fraction of the cost of dev time. For things where scale matters, companies switch to faster languages with more optimization. This is irrelevant for what, 95% of businesses? Granted, probably half of devs are working for big tech where it does matter, but it really doesn't for a lot of us.

In any case, Javascript, which most of us are using more and more, is not that much slower than Java or other low level languages and can be used everywhere.

Re: Why Do Computers Use So Much Energy?

#25

Post by kalenx »

lucideer wrote: post #12

> Precise estimates vary, but currently about 5 percent of all energy consumption in the U.S. goes just to running computers 30% goes on transport. > the human brain is a computer. This particular computer uses some 10–20 percent of all the calories that a human consumes So society's computer uses 5 percent and our own, evolved over millions of years, uses up to 20. I'm not saying computers can't or shouldn't be made…

You clearly can't compare those two percentages.

One of them is over the total energy consumption of the society and the other over the energy needed be keep a human alive.

Computers would not get "magically" more efficient if another industry triples to overall energy consumption of our society, yet that is what your analysis would suggest...

Re: Why Do Computers Use So Much Energy?

#27

Post by visarga »

lucideer wrote: post #19
cvoss wrote: post #17

Earlier quoted context omitted.

The article goes on to explain just how wasteful our computers are, compared to the computations that go on in cells (which is a staggeringly large amount of computation, given their speed and abundance). > But the thermodynamic efficiency of this computation—the amount of energy required by a ribosome per elementary operation—is many orders of magnitude superior to the thermodynamic efficiency of our current artific…

Don't get me wrong, I'm well aware of how inefficient computers actually are compared to cells. But I just don't really see the relevance of the comparison. Computers are so much more efficient that so many things in our world that we could much more easily improve the efficiency of: it would be great to make artificial computers as efficient as our brains but sinking resources into the effort rather than addressing…

The comparison is misguided, I agree. Those teeny 20 watts the brain is using are extracted by killing plants and animals. How about measuring the amount of death per computation?

Also, let's not forget about the enormous time, space and energy used by evolution to make humans. Nothing we invented can rival that kind of resource usage.

Even in Deep Learning, performant models require more data and compute. You can't obtain the same accuracy from running a computer for a day compared to 500 TPUs for a week. Humans have had lots of time to train and evolve, computers not.

Re: Why Do Computers Use So Much Energy?

#28

Post by setquk »

3rdAccount wrote: post #13

This is pretty cool from a low powered 144 computer chip. http://www.greenarraychips.com/

Not really. It's expensive, a dick to program, no FP support and single thread performance is rubbish. A cheap ARM is a better deal now and they are quoted in uA/MHz for performance so you can trade off your performance on the fly.
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