Standby

[Jure Sah]

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Hello,

Here's a simple question: Do you trust standby on your desktop?

I have never used it, but pondering on using it on my HTPC. It seems
attractive using it instead of power-off (it's faster than my TV coming
out of standby, while booting on the other hand...).

The problem really is that Standby is essentially keeping the computer
running, but turning off all the fans. This sounds like a very bad idea
to me. I fear that if I leave my computer in standby, it will eventually
overheat and die.

I know laptops can survive on Standby for months if the battery permits
it, but I suspect wall-outlet powered desktops are still substantially
different in this aspect.

Does anyone have any more experience with Standby on desktops?

Thanks for any help in advance.

LP,
Jure
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[John Doe]

The problem really is that Standby is essentially keeping the
computer running, but turning off all the fans.

If that were true, Yes your computer would overheat and die. If
that were true, any desktop user would shout about it. The answer
should be very easy to find just by looking at reviews.

 

[Benjamin Gawert]

* Jure Sah:

Here's a simple question: Do you trust standby on your desktop?

Yes, I do. I use it regularly on my main desktop because it needs
several minutes to boot up.

The problem really is that Standby is essentially keeping the computer
running, but turning off all the fans. This sounds like a very bad idea
to me.

Yes, it sounds like a vey bad idea. Fortunately it is utterly nonsense.
There are several power states:

- S0: System is on. The CPU is fully up and running; power conservation
operates on a per-device basis.
- S1: System appears off. The CPU is stopped; RAM is refreshed; the
system runs in a low power mode.
- S2: System appears off. The CPU has no power; RAM is refreshed; the
system uses a lower power mode than S1.
- S3: STR (Suspend To RAM), System appears off. The CPU has no power;
RAM is in slow refresh; the power supply is in a reduced power mode.
- S4: STD (Suspend To Disk), System appears off. The hardware is
completely off, but system memory has been saved as a temporary file
onto the harddisk.
- S5: System is off. The hardware is completely off (PSU still provides
Standby voltage to the mainboard), the operating system has shut down;
nothing has been saved.

Really old PCs could only use S1 or S2, and usually some (or all) of the
fans keep running in this mode. However, most better PCs of the last
decade or so support all power states, so only S3 (STR) and S4 (STD) is
used. In S3, only the memory and the memory controller are powered, so
the computer uses a bit of power (usually less than 10W), but the
advantage is that by a press of the button the computer is up and
running again in a couple seconds. S4 means the RAM content is saved to
disk, there is nothing powered in S4, so there is no additional power
consumption. However, starting up the computer takes noticably longer
than from S3 (can be longer than a cold boot).

Neither S3 nor S4 requires any fan to run.

I know laptops can survive on Standby for months if the battery permits
it, but I suspect wall-outlet powered desktops are still substantially
different in this aspect.

No.

Benjamin

 

[Flasherly]

Found a little universally assignable IR block for $5 from Singapore
that I use on the 39" HDTV's remote 00 (for keying channels > 100),
since I've only air. It's a PWR pass-through to the computer that
"remembers" it's last state. PWR=OFF if not ON. Doesn't matter about
brown/blackouts while, always stays in an OFF condition unless
reversed. Set my BIOS to restore system (boot) when PWR detected.
Push one button on the remote, computer boots off the IR block, which
HDTV StandBy picks up as a signal for Display On. One touch, though
slower than standby, but I don't mind waiting 10 seconds to boot.
Clean shutdowns with less a chance for checkdisk, it's for
entertaining, anyway. The other computer, this one stays on 24/7.

 

[Patty]

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Hello,

Here's a simple question: Do you trust standby on your desktop?

I have never used it, but pondering on using it on my HTPC. It seems
attractive using it instead of power-off (it's faster than my TV coming
out of standby, while booting on the other hand...).

The problem really is that Standby is essentially keeping the computer
running, but turning off all the fans. This sounds like a very bad idea
to me. I fear that if I leave my computer in standby, it will eventually
overheat and die.

I know laptops can survive on Standby for months if the battery permits
it, but I suspect wall-outlet powered desktops are still substantially
different in this aspect.

Does anyone have any more experience with Standby on desktops?

Thanks for any help in advance.

LP,
Jure

I use S3 Standby Mode (all fans off) on my system which powers it up quite
quickly. I also use MBM 5 which tells me system temps while in use. When
powering up from Standby the temps are very low, just as if the computer
has been turned off. So no, it doesn't overheat in Standby mode.

Patty

 

[John Doe]

Here's a simple question: Do you trust standby on your desktop?

By the way... What is it?
Obviously you are talking about a process, but are you talking
about a third-party program called "standby", or are you talking
about a function of some flavor of Windows? The term "standby" is
very generic and difficult to find.
--

 

[John Doe]

The problem really is that Standby is essentially keeping the
computer running, but turning off all the fans.

The problem is that I do not know WTF "standby" is.
--

 

[Bug Dout]

The problem really is that Standby is essentially keeping the computer
running, but turning off all the fans.

Quit posting bullshit. Standby typically means the computer is nearly
turned off, lowering power and thus heat significantly, but the RAM
contents are not written to memory. Hybernation means RAM is written to
disk and thus the computer can be completely shut down.

 

[Paul]

The problem really is that Standby is essentially keeping the computer
running, but turning off all the fans.

The power supply in the computer is split in two sections. The "main" section
supplies +3.3V,+5V,+12V,-12V at a total load of perhaps a couple hundred
watts. But the other half of the supply, that runs as long as the switch
is enabled on the back of the supply, provides a much smaller amount of power.
When a computing session ends, the "main" section is turned off, while the
"standby" part of the supply (for +5VSB) continues to run.

There is an example of a power supply circuit diagram here.

http://www.pavouk.org/hw/en_atxps.html

The circuit in the lower left corner of the schematic,
labeled "second power supply", is what creates +5VSB.
It consists of a switching converter on the left, plus
a 78L05 linear regulator to make the +5VSB. The circuit
is not very efficient, but that isn't important. That
circuit also provides a source of power for the TL494.

AC ----- rectifiers --- main caps --- "second power supply" ---> +5VSB

In Standby Suspend to RAM (S3), the RAM continues to be powered
and enough circuitry is running, so that the RAM contents continue
to be refreshed and maintained. When the computer is started later,
the drivers have to do a "warm start", to return the rest of the
hardware to its normal working state, since much of the other circuitry
in the computer is no longer powered. Only a few specific items remain
powered in Standby S3. The LAN chip has a section that remains powered
(to detect Wake On LAN packets). The USB portion of the Southbridge
may remain awake, in order to listen for a waking event from a USB
keyboard or mouse. The sum total of those kinds of loads, may take
about 1 ampere of current from +5VSB. That is 5 watts of power.

The 5W of power dissipated on the motherboard, would be turned into heat.
That 5W can be dissipated by convection or conduction. No fans are needed,
and since +12V is turned off, the fans aren't getting power at this point.

The "second power supply" is about 50% efficient. Not very efficient
at all. Part of the reason, in the case of the above schematic, is
the usage of a linear regulator (the 78L05). Since the "second power supply"
is 50% efficient, it too will emit about 5 watts of heat (inside the
power supply), in response to converting 5 watts to run the motherboard.
Now, the total consumption from the wall is 10 watts. On some power supplies,
you may feel a little warm air coming from the supply by convection.

To dissipate 10 watts of heat, doesn't require fans to be running. In
Standby S3, the CPU is no longer powered. Vcore is off, because there
is no +12V coming from the power supply. Most high power devices will be
off. The video card no longer has power. The hard drives have stopped
spinning (since they're not getting +12V either).

So what dangers are the power supply exposed to ? The main caps are still
charged to 300V. If lightning were to hit near the house, or hit a power
line, the front end of the power supply could be damaged. Maybe, with
the switch off at the back of the computer, the power supply would be
slightly more protected. But due to the other cables connected to the
computer, there are still other paths that could be hit (induced lightning).

So leaving the power supply, with the switch in the ON position on
the back, leaves it with the same "exposure" to AC power events, as
all the other appliances in the house. So, sure, there is probably
some level of risk associated with that.

But the risk of overheating is minimal, since only +5VSB is running, and
+5VSB on a lot of supplies, can supply 2 amperes maximum. The linear
regulator pictured in the above schematic, actually has internal temperature
limiting, and will shut off if it gets too hot.

In S3 or S4, only a small part of the computer is powered, and the element
providing the power, has overtemperature protection. The biggest remaining
exposure, is the same exposure that all appliances in the house experience
by remaining plugged in all the time.

Paul

 

[Bug Dout]

Wow, excellent reply. Learned a lot from that.

 

[John Doe]

FWIW. The subject should be BIOS -- ACPI ...