Home device power use: Difference between revisions
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===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 | |||
: 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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====Monitor==== | |||
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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. | |||
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. | |||
''' | Note that SSD isn't much more efficient than platter in active use, but ''is'' when idle. | ||
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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. | |||
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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====Can we do better?==== | |||
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Yes. | |||
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 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. | ||
In the past, CPUs focused more on the 'how ''fast'' can we go' end, | |||
and | and it's more recent that they also started to think about idle power. | ||
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. | ||
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 may involve some trial and error to even find ''which'' device prevents that, | ||
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 | 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''. | ||
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 | |||
so for servers it's relatively moot | |||
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. | ||
What may be more interesting is the ''idle'' power. | |||
For various desktop and a lot of 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. | |||
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. | which is why this is a bit of a specialization that some do better than others. | ||
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''generally'', C3 is idle but ready to go, and a higher number is turning off even more things. | |||
Core C state | |||
: C3 - L1/L2 caches flushed, stops CPU clock | |||
: C4 - reduces voltage | |||
: C5 - disables cache, reduces voltage more | |||
: C6 | |||
: C7 - C6 and LLC may be flushed. | |||
: C8 - C7 and LLC must be flushed. | |||
Package C state | |||
C3 - | : 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 | |||
C8 | |||
Processor Graphic state | Processor Graphic state | ||
RC0 (Graphics active state) | : RC0 (Graphics active state) | ||
RC1 | : RC1 | ||
RC6 (Graphics | : RC6 (Graphics | ||
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=====Motherboard===== | |||
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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' | |||
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 | Electric water kettle - easily 2000W | ||
: 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: | |||
2000 W * 5 minutes ≈ 160 Watt-hours | |||
160 W * 1 hour ≈ 160 Watt-hours | |||
7 W * 24 hours ≈ 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