Home device power use: Difference between revisions

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{{#addbodyclass:tag_tech}}




===Computers===
===Computers===
tl;dr:
* Assume 40W or more for laptops, idling at 10W with things dialed down
* 150W or more for desktops, idling at 100W (''can'' be much less, if specialized)
:: counting basic monitors (larger and brighter may add more)
:: most gaming machines don't go over 300 or 400W when working hard


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* laptops tend to be ahead in "scaling down power use when idle" because it has more direct implications (battery life)
: good for expectation management of how good you ''might'' get a desktop when you take specific care
:: (not ''all'' of them - certain gamer laptops were only designed to be ''portable'', not to be efficient)
: also suggests using a decent laptoo with a dock as your main computer may be a ''simpler'' solution.


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A desktop PC not designed with power saving in mind may idle around 70..100W.
A desktop PC not designed with power saving in mind may idle around 70..100W.


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: up to 400W on a gaming machine working hard
: up to 400W on a gaming machine working hard


 
'''Laptops''' tend to be ahead in  
 
'''Laptops''' tend to be ahead in "scaling down power use when idle",
: and can sit in the range of 20-40 Watts in regular use, down to maybe 10W idle
: and can sit in the range of 20-40 Watts in regular use, down to maybe 10W idle
: up to 150W when working very hard, maybe more if they are gaming laptops.
: up to 150W when working very hard, maybe more if they are gaming laptops.
: You can basically tell by the power adapter - if it's 60W, it's never going to draw that much.
: You can basically tell by the power adapter - if it's 60W, it's never going to draw that much.
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Those tiny-box computers may use 10-15W - but will also be ''slow''. You're best off using them as thin clients.
====Monitor====
 
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A basic desktop .
: is hard to get to idle under 50W idle or so (not that they can't, but it's not a common requirement without also being a thin client sort of thing)
: will easily cross 100W when doing real work.
 
Beefier desktop may be 100W idle and hundreds when gaming hard.


Assume that a modern LCD panel takes around 25W for a 20" screen.


It can be a more, depending largely on size and brightness (a 30" might be 60W, a 40" might be 100W).


In standby they tend to still use a few watts.


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====Storage====
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[[Image:spinup power.png|thumb|right|211px|Three platter drives made to spin up in sequence]]
Platter may take 4 to 10W while spinning (more while spinning up - assume it might be 20W)


Solid state might be 3 to 5W for SSDs and NVMe in use (can be multiples higher for higher end), and can be negligible while idling.


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Note that for platter, a good portion of which may just be to keep it spinning,
whereas SSD power use is more related to how much you use it (in particular write),
and can be quite low when idle.




'''Can we do better?'''
Note that SSD isn't much more efficient than platter in active use, but ''is'' when idle.


Yes.


But how much will vary.
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====GPU====
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A powerful GPU working hard is probably the hungriest component you have, on par with powerful CPUs. 50 to 200W isn't crazy for a GPU.


Some very informed choices can push a desktop down to 20W idle.  
That said, a moderately powerful GPU might idle at 5 to 15W.
Which is pretty decent power scaling, but still not ideal if you wanted a very power efficient system.
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Note that the level that laptops are at are great for expectation management here about how much you can scale performance ''and'' power in one system - because laptops they have much more direct incentive to have lower idle power (to save battery) ''and'' also be fast enough under use.
====Can we do better?====
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...which, yes, also means that if you want that, laptops ''are'' a nice low-power and potentially-scaling choice.
Yes.  
You might be one dock away from using it as your main PC with no plugging bother.




But how much will vary.


Some very informed choices (mostly just how idle you can make the CPU and hardware components) can push desktop down a bunch.


* if you can accept 15..25W idle, your search becomes a little easier than if you wanted 5..10W


* It is no ''technical'' reason you can't have absolutely ''possible'' to have something that can draw 300W under load and 15W idle, but the ''practical'' amount of research to get that is insane... "if you needed another hobby" levels.
If you can accept 15..25W idle, your search becomes a little easier than if you wanted 5..10W.


* certain gamer laptops were only designed to be ''portable'', not to be efficient
It is no ''technical'' reason you can't have something that can draw 300W gaming hard and 15W idle,  
but the ''practical'' amount of research to get that is "so you wanted another hobby to consume your life?" levels of work,
and the choices will be so specific the information is not that valuable a few years later.






One of the main questions is how well the CPU can idle.  
One of the main questions is how well the CPU can idle.


This did not use to be as much of a design concern as 'how ''fast'' can we go' (except in laptops),
In the past, CPUs focused more on the 'how ''fast'' can we go' end,  
and yet the recent handful of generations have started to think about idle power, and have some decent-to-great choices.  
and it's more recent that they also started to think about idle power.
It still varies, though. {{comment|(Side note: the CPU's TDP rating is almost entirely meaningless - it indicates the amount of cooling you need at maximum use, which is a poor indicator of how much it uses at minimum use)}}
We have decent-to-great choices now, but still have to choose them.
{{comment|(Side note: the CPU's TDP rating is largely meaningless - it indicates the amount of cooling you need at maximum use, which is a poor indicator of how much it uses at minimum use)}}


But also, it's not only ''having'' these deep sleep states, it's also ensuring that they are actually used.
But also, it's not only ''having'' these deep sleep states, it's also ensuring that they are actually used.
Yes that's automatic, ''but'' every piece of hardware('s drivers) could prevent it from going to the deepest sleep states.
Sure that's automatic, ''but'' every piece of hardware('s drivers) could prevent it from going to the deepest sleep states.
It may involve some trial and error to even find ''which'' device it is,  
It may involve some trial and error to even find ''which'' device prevents that,  
and some of it will be motherboard and ''may'' not be changeable.
 
And most motherboards are designed to get them out the door, not for optimal power savings)


This isn't something you can necessarily find in the spec sheets.  
And with bad luck that's motherboard stuff that isn't even changeable.
Most motherboards are designed to get them out the door, not for optimal power savings.
This isn't something you can necessarily find in the spec sheets either.  


If you want to avoid a complex search and some purchases,  
If you want to avoid a complex search and some purchases,  
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Any additional hardware may have its own ideas.  
Any additional hardware may have its own ideas.  
Say, if I have a server that idles at 10W and put in a GPU that idles at 30W, meh.
Say, if I have a server that idles at 10W and put in GPUs that idle at 20W, meh.
 
 
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Note that ''standby'' almost necessarily still uses a few watts of power.
Note that ''standby'' almost necessarily still uses a few watts of power.
: This is largely because the DRAM has to be actively refreshed{{verify}}.
: This is largely because the DRAM has to be actively refreshed{{verify}}.
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====CPU====
=====CPU=====


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The CPU's TDP is an indication of the maximum -- ''only''.  
The CPU's TDP is an indication of the maximum -- ''only''.  


It tends to be on the order of at least 50 or 100W. It seems
TDP tends to be on the order of at least 50 or 100W. It seems
: Mobile may be in the 5..30 range
: Mobile may be in the 5..30 range
: moderate-speed CPUs tend to be in the range of 40..100W
: moderate-speed CPUs tend to be in the range of 40..100W
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When going for power efficient
When going for power efficient, know that watts per job done doesn't vary a lot, so if you expect it to be busy (e.g. for certain kinds of servers) it's a relatively moot point.
know that watts per job done doesn't vary ''too'' much,
 
so for servers it's relatively moot{{verify}}.
And a a gamer PC during gaming will ''always'' be a power hog.
And a a gamer PC during gaming will ''always'' be a power hog.


For desktop and mobile it's not so much about what it can do working hard,
and much more about how much it can scale down when relatively idle,
because that might be most of the time.




There are sometimes mild-looking variants where one CPU idles at dozens and another at a handful of Watts.
What may be more interesting is the ''idle'' power.


When looking for these, the C states are an indication of how deeply it's designed to sleep,
For various desktop and a lot of mobile it's not so much about what it can do working hard,
but it's a far-from-perfect indication.  
and much more about how much it can scale down when relatively idle, because that might be most of the time.


That said, the deeper it wants to sleep, the more than any installed hardware needs to support all that,
 
which is why this is a bit of a specialization.
 
 
The deeper a CPU wants to sleep, the more this is a thing about cooperation of hardware,
which is why this is a bit of a specialization that some do better than others.




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During the CPU C3 State, the CPU clock generator is turned off.
''generally'', C3 is idle but ready to go, and a higher number is turning off even more things.
During the CPU C6 State, the power to all cache is turned off.  


Core
 
C3 - L1/L2 caches flushed, stops clocks
Core C state
C4 - reduces voltage
: C3 - L1/L2 caches flushed, stops CPU clock
C5 - disables cache, reduces voltage more
: C4 - reduces voltage
C6  
: C5 - disables cache, reduces voltage more
C7 - C6 and LLC may be flushed.
: C6  
C8 - C7 and LLC must be flushed.
: C7 - C6 and LLC may be flushed.
: C8 - C7 and LLC must be flushed.
 
Package C state
: C2 - all CPU cores in C6
: C3 - all CPU cores in C6, graphics in any state?
: C6 - Package C3 + BCLK is off + allows voltage reduction
: C8 - cores requested C8 + disables last level cache
: C10 - Package C8 + display in PSR or powered, all VRs at PS4 + crystal clock


Processor Graphic state
Processor Graphic state
RC0 (Graphics active state)  
: RC0 (Graphics active state)  
RC1
: RC1
RC6 (Graphics  
: RC6 (Graphics  
 
Package
C2 - all CPU cores in C6
C3 - all CPU cores in C6, graphics in any state?
C6 - Package C3 + BCLK is off + allows voltage reduction
C8 - cores requested C8 + disables last level cache
C10 - Package C8 + display in PSR or powered, all VRs at PS4 + crystal clock




https://edc.intel.com/content/www/us/en/design/ipla/software-development-platforms/client/platforms/alder-lake-desktop/12th-generation-intel-core-processors-datasheet-volume-1-of-2/001/package-c-states/
https://edc.intel.com/content/www/us/en/design/ipla/software-development-platforms/client/platforms/alder-lake-desktop/12th-generation-intel-core-processors-datasheet-volume-1-of-2/001/package-c-states/
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====GPU====
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A powerful GPU working hard are probably the hungriest component you have, on par with powerful CPUs. 50 to 200W isn't crazy for a GPU.
That said, a moderately powerful GPU might idle at 5 to 15W.
Which is pretty decent, but not ideal if you wanted a very power efficient system.
-->
====Monitor====
<!--
Assume that a modern LCD panel takes around 25W for a 20" screen.
It can be a more, depending largely on size and brightness (a 30" might be 60W, a 40" might be 100W).
In standby they tend to still use a few watts.
-->
====Storage====
<!--
[[Image:spinup power.png|Three drives made to spin up in sequence]]
Platter may take 4 to 10W while spinning (more while spinning up - assume it might be 20W)
SSD might be 3 to 5W for SSDs and NVMe in use - but this can be multiples higher for higher end.
Note that for platter, a good portion of which may just be to keep it spinning,
whereas SSD power use is more related to how much you use it (in particular write),
and can be quite low when idle.




-->


====Motherboard====
=====Motherboard=====


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Your component draw is, roughly:
* Idle draw is often around 70W when doing nothing or just browsing wikipedia
* Peak draw is often between 100W and 200W on most regular hardware
* When  adding fancier CPUs, and even vaguely capable GPUs, you can more easily look at 400W total




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: In part because you can't perfectly predict how much current will be drawn from the different voltage rails, so you need some leeway
: In part because you can't perfectly predict how much current will be drawn from the different voltage rails, so you need some leeway
: In part because you often can't tell the quality of the PSU, so you build in a margin
: In part because you often can't tell the quality of the PSU, so you build in a margin
And when estimating that peak, think 70W when poking at a browser, 100 to 200W in more active use, and maybe 300W to 400W while gaming.




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Amplifiers tend to use oldschool transformers instead of switch-mode power.  
Amplifiers tend to use oldschool transformers instead of switch-mode power.  


This is a great way to avoid noise from the power supply that switch-mode might easily introduce, but also makes it harder to push down the baseline power use.
This is a great way to avoid noise from the power supply that switch-mode might easily introduce,
but also makes it harder to push down the baseline power use.
 
 
Assume that it ''might'' be using 15-35W just for being powered on, making no sound.
Assume that it ''might'' be using 15-35W just for being powered on, making no sound.
It's often better, but if you're squeezing down on power use, measure it.
: (I've found that some receivers that have a "just a red LED" standby, what you would consider ''off'', might actually still consume most of that baseline 20W)


It'll go up when actually making sound, but people overestimate how much - in a small to moderate room, 20W to 30W of sound is ''loud''.


And yes, it'll go up when actually making sound, but people overestimate how much - in a small to moderate room, 20W to 30W of sound is ''loud''.


It's often better, but if you're squeezing down on power use, measure it.
I've found that modern receivers that have use 20W just in their "just a red LED" standby mode -- what ''you'' would probably consider off.


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'''Beefy heaters'''
'''Beefy heaters'''


Electric water kettle - easily 2kW, but when you use it for 10 minutes per day,
Electric water kettle - easily 2000W
so the same total power as 10W thing that's on all day.
: note that 2000W used 10 minutes per day is roughly the same as a 10W light thing that's on all day
 


Under-sink water boiler
Under-sink water boiler
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: but in the end little difference from the water boiler - it's just about concentrating ''when'' you're heating. The only real difference is that you don't have to isolate it against heat loss
: but in the end little difference from the water boiler - it's just about concentrating ''when'' you're heating. The only real difference is that you don't have to isolate it against heat loss


(the 2kW is not a device limitation as such -- it's an assumed safety limit, because a single house socket cannot be assumed to supply more unless it's ''made'' for it and probably has a special plug)




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===Water cookers===
===Water cookers===
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Yes, they may draw 1000 or 2000W.
They will also only do so for 5 minutes, so they're sort of equivalent to running a 150W thing for an hour or a 6W thing 24/7:


Yes, they may draw 1000 or 2000W. They will also only do so for 5 minutes, so they're sort of equivalent to running a 150W thing for an hour or a 6W thing 24/7.
2000 W * 5 minutes &#x2248; 160 Watt-hours
  160 W * 1 hour   &#x2248; 160 Watt-hours
    7 W * 24 hours  &#x2248; 160 Watt-hours


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Latest revision as of 16:38, 20 April 2024


Computers

tl;dr:

  • Assume 40W or more for laptops, idling at 10W with things dialed down
  • 150W or more for desktops, idling at 100W (can be much less, if specialized)
counting basic monitors (larger and brighter may add more)
most gaming machines don't go over 300 or 400W when working hard


Monitor

Storage

GPU

Can we do better?

CPU
Motherboard

Power Supplies

Audio amplifier

Smaller devices

Heaters and coolers

Water cookers

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