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How much power does a computer use when turned OFF

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a b ) Power supply
November 28, 2010 5:10:05 AM

I know everything but the power button is turned off, but how much power is that. It can't be none becuase if it was none then pushing the button in the front would not start the computer. You would need to use a hard-switch like the one on the back of the PSU.

:bounce: 

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November 28, 2010 5:18:26 AM

It's effectively none. Under 1 watt.
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a b ) Power supply
November 28, 2010 5:22:48 AM

cjl said:
It's effectively none. Under 1 watt.



I know that silly, but exactly how much. :lol: 


There is no reason to know this... but I am kinda bored and want to know =P Also could not find it via google.
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a c 92 ) Power supply
November 28, 2010 5:47:05 AM

The max would be whatever the 5VSB would be? If your PSU would do 3A on that rail, then 15W.

I'm not sure if the power switch works off of that rail, or the 12V rail. I would guess higher then 1W, but less then 5W in most cases. 1W just seems to low to me.
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a b ) Power supply
November 28, 2010 5:49:01 AM

4745454b said:
The max would be whatever the 5VSB would be? If your PSU would do 3A on that rail, then 15W.

I'm not sure if the power switch works off of that rail, or the 12V rail. I would guess higher then 1W, but less then 5W in most cases. 1W just seems to low to me.


I never said it was high, I just how you think the computer is off and is using no power, but is really using at-least some power.
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a b ) Power supply
November 28, 2010 5:52:42 AM

oh well I am going to sleep cya later
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November 28, 2010 6:18:43 AM

Well, on my computer at least, my power meter (with 1 W accuracy) reads 0W when the computer is off. There really shouldn't be significant power draw when it is off. Standby or sleep mode is where you'll see power levels closer to the 5VSB max.
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a b ) Power supply
November 28, 2010 7:46:01 AM

well my computer powers all USB ports even after shutdown... so i reckon its probably taking more than 1W...
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November 28, 2010 9:04:41 AM

Definitely if you leave USB peripherals powered on.
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a b ) Power supply
November 28, 2010 9:54:35 AM

forget about USB peripherals being powered on... i tried modded usb fans to cool my AV receiver and they were just running even with the PC shutdown... that was when i found that USB'c are constantly powered on...
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a c 144 ) Power supply
November 28, 2010 2:01:35 PM

My Kill-a-Watt meter indicates 1 watt with system off and no USB devices plugged in.

If you think about it, that's really quite a bit of power. That's 200 ma at 5 volt out of the standby power supply just to monitor the green wire in the PSU.

Or more likely, because 1 watt is the resolution of the meter, the reading is the result of quantization errors in the meter.
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a b ) Power supply
November 28, 2010 4:05:33 PM

What about the little yellow light on my mobo, how much does that use, its on all the time. :heink: 
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a b ) Power supply
November 28, 2010 4:18:25 PM

i tested out a random pc in the house, an amd sempron socket a/462 with a 200w psu. it started at 0w when just plugged in and went up to 4 withing 10 seconds.

i tested out a random laptop in the house (ibook g4 1.07ghz), plugged in, off, done charging, 2w.
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November 28, 2010 7:12:52 PM

Whoa, thanks for the tip. I'll be checking if all my old junk puters are plugged in or not!
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a b ) Power supply
November 28, 2010 9:42:26 PM

shovenose said:
i tested out a random pc in the house, an amd sempron socket a/462 with a 200w psu. it started at 0w when just plugged in and went up to 4 withing 10 seconds.

i tested out a random laptop in the house (ibook g4 1.07ghz), plugged in, off, done charging, 2w.


varis said:
Whoa, thanks for the tip. I'll be checking if all my old junk puters are plugged in or not!



^^^ Thanks thats what I was looking for.


Now I don't pay for power *still live with my parents I'm not 18 =p* but how much on average is 4 w of power
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a b ) Power supply
November 28, 2010 9:46:16 PM

varis said:
Whoa, thanks for the tip. I'll be checking if all my old junk puters are plugged in or not!



Yes if you want to be super green then you should unplug ALL unused stuff =p


but imo that is more work then it is worth..

I know they sell power bricks that blocks all power when turned off tho




*I thought this video was very fitting =p*
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a b ) Power supply
November 28, 2010 9:50:03 PM

abully said:
well my computer powers all USB ports even after shutdown... so i reckon its probably taking more than 1W...



How much does the average USB device use?
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a b ) Power supply
November 28, 2010 10:07:17 PM

less than 5w.
usb runs at 5v, and usb spec allows a max of 900ma(0.9a).
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a b ) Power supply
November 28, 2010 10:20:07 PM

shovenose said:
less than 5w.
usb runs at 5v, and usb spec allows a max of 900ma(0.9a).



That is still more then I would have ever think that it would use.


You normally think OFF = OFF not super idle mode. =)
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a b ) Power supply
November 28, 2010 10:39:29 PM

well waddya think all those little standby lights on dvd players, stereos, tvs, are doing :) ?
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a c 288 ) Power supply
November 29, 2010 2:12:25 AM

Off is a relative term in electronics, because there is almost always something watching to see when it gets turned On. A normal USB device is ~500mA i believe, so thats about 2.5W, depending on your board, your load on the VSB can be a bit different but 1A would be about the most for a normal board, so thats about 5W.

5W on a computer that is plugged in 24/7/365 is 43.8kW over the course of the year, if you say its about 15 cents per kWh then the standby power costs you $6.57 over the course of the whole year, not a ton.
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a b ) Power supply
November 29, 2010 3:04:01 AM

hunter315 said:
Off is a relative term in electronics, because there is almost always something watching to see when it gets turned On. A normal USB device is ~500mA i believe, so thats about 2.5W, depending on your board, your load on the VSB can be a bit different but 1A would be about the most for a normal board, so thats about 5W.

5W on a computer that is plugged in 24/7/365 is 43.8kW over the course of the year, if you say its about 15 cents per kWh then the standby power costs you $6.57 over the course of the whole year, not a ton.



That sums up this topic I believe. ;) 
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a b ) Power supply
November 29, 2010 3:04:23 AM

Best answer selected by Randomacts.
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a b ) Power supply
November 29, 2010 6:03:08 AM

This topic has been closed by Maziar
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