Suspending desktop computer. CPU Fan

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Hi all.

When suspending my desktop computer, the power supply fan switchs off, but
the CPU fan does'nt...

Perhaps this is normal because desktop computers are not though for being
The fact of the CPU fan to switch off, is something that could be configured
in the OS or is up to hardware matters? (I've looked in the "Power
management" menu in Windows, but could'nt find anything usefull).


Athlon AMD K7 on  Gigabyte motherboard.
"BlueCool" CPU fan.
Win XP

Re: Suspending desktop computer. CPU Fan

"Sergio T.P." wrote:
Quoted text here. Click to load it

All I can do, is tell you about hardware.

The power supply has two sets of outputs, the main outputs, and +5VSB.
The main outputs run when the computer is doing its real work. When the
computer is suspended/sleeping, the contents of RAM are maintained
by +5VSB, and the main outputs are off.

PSU states
1) PSU switch set to "0". Main outputs off, +5VSB off.
2) PSU switch set to "1". Running computer state. Main outputs on. +5VSB on.
3) PSu switch set to "1". Sleeping computer state. Main outputs off.
+5VSB on.

The CPU fan on a desktop computer runs from +12V. That is one of the
main outputs. And that would suggest to me that you are entering S1
"Monitor switched off" and not S3 "Suspend to RAM". It sounds like
the main outputs are still running.

The fact that the power supply fan switches off, is not consistent with
the state of the CPU fan. Usually, the CPU fan should follow the
state of the PSU fan, as they are both powered by +12V.

If you wish to fix up your "sleep" state for the computer, first
check in the BIOS, that the correct option has been selected. Sometimes
there is mention of S3 in there. In Windows, you can use tools like
"dumppo", downloadable from Microsoft, to query and repair the selection
of ACPI S states. Using administrative override in dumppo can allow
your computer to enter S3. This assumes that in Device Manager, the
entry for "Computer", lists ACPI as being supported.

Sometimes a non-compliant driver or hardware, can prevent the ACPI states
from working properly. And dumppo is the only tool I know of, to help
debug the problem. It is a tiny (command window) program, downloadable
from .


Re: Suspending desktop computer. CPU Fan

No, you're CPU fan will run untill the VDD on cpu is at 0 (meaning no
power to CPU AT ALL)

Because where there is power (not neccesarilly cycles taking place)
there is power dissipation (heat)

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