how much power does a system use while on standby?

murphy55d

Lifer
Dec 26, 2000
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anyone know?

same with a printer... i have a lexmark laser printer and its more convenient to leave it on standby rather than turn it on and off.

can you compare it to something else? like leaving a TV on... or a lamp... ?
 

IamDavid

Diamond Member
Sep 13, 2000
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Depending on configuration, Standby and Hibernate typically consume less than 5W of power, so this betters Energy Star® standards which require power consumption below 15W, a 67% reduction.

**Taken from Dell website.
 

Keego

Diamond Member
Aug 15, 2000
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Hibernate means the computer is off... so it wouldn't be taking up any power.
 

IamDavid

Diamond Member
Sep 13, 2000
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Originally posted by: Keego
Hibernate means the computer is off... so it wouldn't be taking up any power.

Hibernation doesn't completely shut down the system. It transfers the data in the memory to the hard drive then the system goes into standby. So it still uses some power, just not much. At least this is how I understand it, maybe I am wrong.
 

Mark R

Diamond Member
Oct 9, 1999
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It transfers the data in the memory to the hard drive then the system goes into standby.

No. It transfers all the data in memory the the HD, then switches off - completely. I've hibernated a PC, unplugged it while I moved house, and it restarted exactly as I had left it.

When the PC next boots, the OS detects the hibernation file, and loads that instead of going through its normal startup sequence.

There is a similar standby mode, called suspend to RAM - the data is left in RAM, and the system powered off - but the RAM is kept energised by 'always on' part of the PSU (the one that allows your PC to switch itself on after a wake up timer, or wake-on-LAN event). If you unplug the PC from the mains then it will lose the memory contents and will not resume.

In either case, the amount of power used by the PC is very low (probably less than 5W in both cases).
 

Keego

Diamond Member
Aug 15, 2000
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Originally posted by: Mark R
It transfers the data in the memory to the hard drive then the system goes into standby.

No. It transfers all the data in memory the the HD, then switches off - completely. I've hibernated a PC, unplugged it while I moved house, and it restarted exactly as I had left it.

When the PC next boots, the OS detects the hibernation file, and loads that instead of going through its normal startup sequence.

There is a similar standby mode, called suspend to RAM - the data is left in RAM, and the system powered off - but the RAM is kept energised by 'always on' part of the PSU (the one that allows your PC to switch itself on after a wake up timer, or wake-on-LAN event). If you unplug the PC from the mains then it will lose the memory contents and will not resume.

In either case, the amount of power used by the PC is very low (probably less than 5W in both cases).

Thanks ;)
 

bsobel

Moderator Emeritus<br>Elite Member
Dec 9, 2001
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No. It transfers all the data in memory the the HD, then switches off - completely. I've hibernated a PC, unplugged it while I moved house, and it restarted exactly as I had left it.

I know I jumping into the thread late, but to clarify hibernate may not mean the power is completely off. It depnds on the hibernate power state configured in the bios S1-S5. During hibernate the state is stored to disk, but often there is enough power available to run the NIC/Modem for wake on lan/wake on ring events.

Bill
 

ssanches

Senior member
Feb 7, 2002
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There are various states of standby. Here's something I can remember:

S1 - Standby -The HDD and Monitor and CPU go into lower power states, other peripeherals also may go into power management states, depending the extent to which they support it.

S3 - Standby - Suspend to RAM (STR) (All devices go into a lower power state /off, the only thing running is the RAM (though it's only refreshed, no transfers are being made) The only SMPS rail running is the +5VSB (Standby Voltage). Most SMPSes supply around 2A power on this rail, so I'd guess the max power consumption by the PC would be 10 watts in standby (plus the overhead for the efficiency of the SMPS; usually the most efficient ones are rated at 75% efficiency). I'd estimate below 20W including the SMPS efficiency overhead. If you turn off your PC, it causes data losses and all unsaved work is lost.

S4 - Hibernate - In this mode, an image of the memory is taken and placed on a scratch file on the HDD and then the system powers down. You may unplug the PC and take it around :) and when you switch it on again, the image is restored to the RAM and you can continue working normally. When you unplug it, there is 0W power usage

S5 - Power off - Shutdown state
 

ssanches

Senior member
Feb 7, 2002
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Okay, here's something I got from MSDN library: :)

Linky

System Sleeping States S1, S2, S3, S4
States S1, S2, S3, and S4 are the sleeping states. A system in one of these states is not performing any computational tasks and appears to be off. Unlike a system in the shutdown state (S5), however, a sleeping system retains memory state, either in the hardware or on disk. The operating system need not be rebooted to return the computer to the working state.

Some devices can wake the system from a sleeping state when certain events occur, such as an incoming call to a modem. In addition, on some computers, an external indicator tells the user that the system is merely sleeping.

With each successive sleep state, from S1 to S4, more of the computer is shut down. All ACPI-compliant computers shut off their processor clocks at S1 and lose system hardware context at S4 (unless a hibernate file is written before shutdown), as listed in the sections below. Details of the intermediate sleep states can vary depending on how the manufacturer has designed the machine. For example, on some machines certain chips on the motherboard might lose power at S3, while on others such chips retain power until S4. Furthermore, some devices might be able to wake the system only from S1 and not from deeper sleep states.

System State S1
System state S1 is a sleeping state with the following characteristics:

Power consumption
Less consumption than in S0 and greater than in the other sleep states. Processor clock is off and bus clocks are stopped.
Software resumption
Control restarts where it left off.
Hardware latency
Typically no more than two seconds.
System hardware context
All context retained and maintained by hardware.

System State S2
System state S2 is similar to S1 except that the CPU context and contents of the system cache are lost because the processor loses lower. State S2 has the following characteristics:

Power consumption
Less consumption than in state S1 and greater than in S3. Processor is off. Bus clocks are stopped; some buses might lose power.
Software resumption
After wake-up, control starts from the processor's reset vector.
Hardware latency
Two seconds or more; greater than or equal to the latency for S1.
System hardware context
CPU context and system cache contents are lost.
System State S3
System state S3 is a sleeping state with the following characteristics:

Power consumption
Less consumption than in state S2. Processor is off and some chips on the motherboard also might be off.
Software resumption
After the wake-up event, control starts from the processor's reset vector.
Hardware latency
Almost indistinguishable from S2.
System hardware context
Only system memory is retained. CPU context, cache contents, and chip set context are lost.

System State S4
System state S4, the hibernate state, is the lowest-powered sleeping state and has the longest wake-up latency. To reduce power consumption to a minimum, the hardware powers off all devices. Operating system context, however, is maintained in a hibernate file (an image of memory) that the system writes to disk before entering the S4 state. Upon restart, the loader reads this file and jumps to the system's previous, pre-hibernation location.

If a computer in state S1, S2, or S3 loses all AC or battery power, it loses system hardware context and therefore must reboot to return to S0. A computer in state S4, however, can restart from its previous location even after it loses battery or AC power because operating system context is retained in the hibernate file. A computer in the hibernate state uses no power (with the possible exception of trickle current).

State S4 has the following characteristics:

Power consumption
Off, except for trickle current to the power button and similar devices.
Software resumption
System restarts from the saved hibernate file. If the hibernate file cannot be loaded, rebooting is required. Reconfiguring the hardware while the system is in the S4 state might result in changes that prevent the hibernate file from loading correctly.
Hardware latency
Long and undefined. Only physical interaction returns the system to the working state. Such interaction might include the user pressing the ON switch or, if the appropriate hardware is present and wake-up is enabled, an incoming ring for the modem or activity on a LAN. The machine can also awaken from a resume timer if the hardware supports it.
System hardware context
None retained in hardware. The system writes an image of memory in the hibernate file before powering down. When the operating system is loaded, it reads this file and jumps to its previous location.