What is the difference between stand by mode and hibernation? How do they work?

At hibernation, the data in the main memory is written to a specific hidden file (in Windows, the hiberfil.sys file that is written to drive C:A).

This file is the size of the entire RAM and always exists, whether the computer is in hibernation or not.

You can deactivate hibernation with the console command “powercfg -h off” (hiberfil.sys disappears) and re-enable it with the same command with the parameter +h.

When reactivating from hibernation, all you need to do is write the contents of hiberfil.sys back into the main memory, which is much faster than a complete boot operation.However, the computer is also switched off – just like your automatic shutdown.

Standby means that the memory content is kept in the stand-by state.For example, the hard drives, graphics card, etc. are switched off.

For the stand-by state, the computer still needs energy, because the motherboard is supplied with voltage via the 5-volt line, so that the main memory remains active.

However, stand-by is the fastest way to wake up the computer from a state that consumes less energy than full operation.

Stand-By corresponds to S3 in the following list (STR, Suspend to RAM), the hibernation state S4 (STD, Suspend to Disk).

On Windows, the power-saving options can be set even more precisely:

Optimally adjust power options in Windows .

The various energy-saving states according to ACPI are defined as follows (cited by htpc-news.de):

G0 (S0) – Working system works as we know it.
Sleeping CPU in Stop Grant (C1), screen off, RAM in self-refresh, all system timers off (except for RTC), power supply continues to run, PCI bus fully powered (graphics card fan is running).

Wake up in the S0 within a few cycle cycles.
b>Sleeping Slightly deeper sleep mode than S1, CPU without voltage.The wake-up time is slightly longer than S1.
Sleeping Suspend-to-RAM (STR): The operating system secures the system state in main memory (RAM) and then switches the power supply to the soft-off state, i.e. the only supply of the motherboard via the 5-volt standby line.This also requires the complete RAM to be supplied in self-refresh mode. Wake up a few seconds. Disadvantage: “Sensitive” mode, already a single wrong driver or an unsafe 5 volt standby supply cause the system either not to switch to the S3 at all or to wake up reliably.
Tip:If a fan is still spinning in standby or the CD-ROM drawer is unmoving, it is not the S3 (then probably S1 or APM standby).
b>Sleeping Suspend-to-Disk (STD) / Hibernate: The operating system backs up the system state to a special file on the hard drive and then switches the power supply to the soft-off state; the only supply of the motherboard via the 5 volt standby line.The system can be disconnected from the networkcompletely.Wake up: Complete boot operation of the BIOS, operating system then starts as if from the S3, but start time depends on the size of the installed memory, and the speed of the hard drive after startup. Modern BIOSse turn on UDMA mode at startup, which greatly speeds up the wake-up from the S4.
SoftOff operating system shuts down and switches the power supply to soft-off state.
With an SSD, waking up from S4 and S5 can be significantly accelerated.The other states keep the data in RAM and therefore do not benefit from a fast hard drive.

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