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What happenes when the computer goes to sleep?

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November 30, 2009 8:15:51 PM

When the computer goes to sleep which components are turned off? which components are turned on? and if is there a third situation in which the component is at when the computer is "sleeping"?

Just to confirm my thought, when the computer is sleeping, the RAM stays turned on? If so, it's not good for the long term to always send the computer to sleep instead of fully turning off?

Thank you.

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November 30, 2009 11:27:11 PM
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In sleep mode the CPU powers down to it's minimum state, the hard drives are powered off, the screen is powered off, and the USB ports are either powered on or off depending on the BIOS and OS settings (you may want to leave the USB ports powered on so that you can wake up the computer by pressing a key on the keyboard).

The main component that stays powered up is RAM memory - this allows a fast restart because the OS and programs don't have to be reloaded from disk. Also, again depending on the BIOS and OS settings, the system can be woken up by a timed event or by special network packets.

On my Core i7 system with 12GB of RAM, "sleep" mode draws about 8 watts from the wall socket, compared to about 5 watts when powered off. When I don't plan to use the computer for a while I shut it down completely and cut power to the power supply using an under-monitor power switching unit.
December 1, 2009 2:28:18 PM

Thank you for your explanation, can you explain a little bit more about the watts consuming during the different states?

Thank you.
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December 1, 2009 3:16:12 PM

I don't know myself but you can find out using one of those Watt meters between a laptop and the wall. If I get the time I'll check it with my TX2500. The laptop consumes about 20W idle. If I get the time to check, I'll let you know what it is in sleep.
December 1, 2009 10:07:47 PM

As enzo mentioned, I used a "Kill-a-Watt" meter to measure the power draw of my system during "sleep" and "off" states.
December 2, 2009 3:28:57 PM

sminlal I understand that you already measured the watt consumption in both states. can you post them please?

One of my questions hasn't been answered; does sending the computer to sleep, instead of turning off for large periods of time, harms/damages the RAM?

Thank you.
December 2, 2009 4:18:25 PM

What happens when the computer goes to sleep? it dreams of electric sheep.
December 2, 2009 6:02:35 PM

Mousemonkey said:
What happens when the computer goes to sleep? it dreams of electric sheep.

http://xkcd.com/571/
If androids someday DO dream of electric sheep, don't forget to declare sheepCount as a long int.
December 2, 2009 6:20:57 PM

l_r_c_t said:
sminlal I understand that you already measured the watt consumption in both states. can you post them please?
As I mentioned in my original post, the system draws 8 watts in sleep mode and 5 watts when "powered down". And of course it draws 0 watts when I turn off the master switch on my power switching unit to prevent any juice getting to the system at all.

RAM will not be damaged by leaving the system in "sleep" mode, nor by leaving the system powered on continuously. I suppose one could make an argument that actually turning the system off and on is more harmful since that cycles the modules thermally. In the old days of DIP chips and SIMM modules, over time the chips/modules would actually work their way out of the sockets due to the thermal changes and from time to time you'd have to reseat them. But modern DIMMs have locking clips to prevent this, and any physical damage caused by the thermal gradients has got to be so gradual as to be negligible when compared to the useful life (5-10 years) of a typical DRAM module.
December 2, 2009 6:55:34 PM

sminlal, you are very helpful with your explanations.

I would like to ask you two more questions:

1) Is there any damage to the whole hardware if leaving the system in sleep mode instead of turning off (of course in the long term), if not, why is there a turning off mode at all (Except of the power saving)?

2) what is this device that prevents the electricity to "leak" to the computer while being turned off? does the divider with the small red switch (on/off) do the same work (preventing "leakage" of electricity to the computer)?

Thank you.

P.S. From what I noticed, when the computer is turned on after being in sleep mode, the system doesn't work quiet right, like it works after being turned on from a complete shutdown. Any explanation?
December 2, 2009 11:16:29 PM

(1) There shouldn't be any damage to the hardware at from leaving the system in "sleep" mode. The biggest reason to shut down the computer completely is to save power. The other reason is that using sleep mode doesn't remove programs from memory - over time the system could potentially accumulated unwanted things like leaked handles or unreleased memory handles that can only be cleared by a reboot.

(2) Below is a picture of my power switch. It's basically a power bar that sits underneath my monitor and has switches to make it easy to turn off individual pieces of equipment (my printer or scanner, for example) as well as having a "master" switch that turns off everything. The power switch plugs into the wall socket, and my computer power cord plugs into the back of the power switch. If I'm going to be away from the computer for a while I shut it down and then turn off the power switch so that I don't waste the 5 watts of power it consumes in "power off" mode.



(P.S.) There shouldn't be any difference in the way the system works after coming back from "sleep" mode. I've never seen any on my system. If there are problems, my guess would be that there's some device driver that's to blame since that's the major type of software that needs something special done when entering and leaving sleep mode.
December 2, 2009 11:28:16 PM

l_r_c_t said:
sminlal, you are very helpful with your explanations.

I would like to ask you two more questions:

1) Is there any damage to the whole hardware if leaving the system in sleep mode instead of turning off (of course in the long term), if not, why is there a turning off mode at all (Except of the power saving)?

2) what is this device that prevents the electricity to "leak" to the computer while being turned off? does the divider with the small red switch (on/off) do the same work (preventing "leakage" of electricity to the computer)?

Thank you.

P.S. From what I noticed, when the computer is turned on after being in sleep mode, the system doesn't work quiet right, like it works after being turned on from a complete shutdown. Any explanation?


-The turning off mode is the best because it clears your memory. IF your memory gets clogged with a bunch of garbage, a reboot will completely wipe since its volitale meaning it needs power to hold data, once power is gone it loses everything. So in standby since your ram is always on, it can get clogged after a while.

-And the easiest and most garenteed way of preventing the electric leak is to just unplug the power cord from the wall :)  or most powersupply's have switches in the back but not sure about wether it prevents electric leaks.
December 5, 2009 7:07:10 PM

Is this memory clean can be done using a special software, for example "Smart Ram" of Iobit?

This power switch that you own, being an electrical device, doesn't consume electricity while plugged into the wall socket? if so, what is the saving?

My second question in the last post wasn't answered, if you can answer it, I have a socket divider, with a red switch that turns on/off the whole sockets (and of course all the devices connected to this sockets), a picture of one similar to mine: .
The question was whether this device saves the watts consumed by the system while being in "turn off" mode?

Thank you.
December 5, 2009 9:02:40 PM

The power switch I own (the one in the photo I posted) is just a fancy power bar with a switch for every outlet and one "master" switch. It's only function is to turn the power off or on - it consumes no electricity on it's own.

The power bar you pictured is the same - it won't consume any of it's own electricity. It's only functions are to (a) let you plug in lots of devices, and (b) turn them all off or on.

All modern computers consume a small amount of electricity even when they're turned off (as I mentioned, mine consumes 5W, which adds up to about 3 or 4KWh over a month, equal to about 20-25 cents worth of electricity where I live).

It's not just computers, all kinds of equipment does this. Anything that can be turned on or off with a remote control needs to constantly watch for the "power on" signal from the remote, and that takes a little bit of power.

If you use a power bar like the one you pictured and if you turn its switch "off" AFTER you shut down your computer and before you start it up, it will prevent the computer from using ANY electricity.

I like my switch because the switches are right at hand. A power bar like the one you pictured is more likely to be underneath the desk. In that case it might be just as easy to turn off the computer's main power switch (the one beside the power cord connection) which will do the same thing.
December 6, 2009 5:14:34 PM

If the whole unneeded consumption (computer in "Turn off" mode) sums up to 4kw which is equal to about 50 cent (where I live) it doesn't worth the trouble of turning it on/off every time that I want to use the computer.
As far as I know, the whole electronic devices (including speakers, router etc) consume electricity, in "Turned off" mode, even if not waiting for a turning on order from a remote control, and if true, the whole unneeded consumption can reach to another 4kw that would be equal to 50 cent.

At the bottom line, if the saving is so low, 1-2$ a month, why spending money on a "Master Switch" like yours, or bothering myself each time to reach the red switch and turning the sockets on/off.

Any way, sminlal[b/] your explanations were very helpful. Thank you for the dedication and the patience.
blackhawk1928 Thank you.
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