PC turned itself on. PME ?

  • Thread starter Thread starter Jethro
  • Start date Start date
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Jethro

HI guys,

I'm building up a mobo I inherited, MSI P4 (not sure of exact ID) with
an award BIOS. It's plugged into my (wireless) router, and the modem
is connected to my phone line.

Last couple of days, my wife has found it on, even though it was
switched off the night before. This is puzzling me. One thing which
may be a clue, is when I plugged the modem in, Sunday, the PC turned
on !

After looking in the BIOS, I found a power-management setting "Wake on
PME" which was enabled (now disabled !). Having looked up PME to mean
Power Management Event, I was wondering if there was something in the
modem, or router which was causing them to issue a PME signal ?

Can anyone confirm or dismiss this theory ?
 
Jethro said:
HI guys,

I'm building up a mobo I inherited, MSI P4 (not sure of exact ID) with
an award BIOS. It's plugged into my (wireless) router, and the modem
is connected to my phone line.

Last couple of days, my wife has found it on, even though it was
switched off the night before. This is puzzling me. One thing which
may be a clue, is when I plugged the modem in, Sunday, the PC turned
on !

After looking in the BIOS, I found a power-management setting "Wake on
PME" which was enabled (now disabled !). Having looked up PME to mean
Power Management Event, I was wondering if there was something in the
modem, or router which was causing them to issue a PME signal ?

Can anyone confirm or dismiss this theory ?
Click to expand...

You should also look in your BIOS for Wake on Lan - perhaps the router is
sending a wake-up signal that way. You should turn off your PC at the wall
when not in use as it uses power even when 'turned off'
 
Jethro said:
HI guys,

I'm building up a mobo I inherited, MSI P4 (not sure of exact ID) with
an award BIOS. It's plugged into my (wireless) router, and the modem
is connected to my phone line.

Last couple of days, my wife has found it on, even though it was
switched off the night before. This is puzzling me. One thing which
may be a clue, is when I plugged the modem in, Sunday, the PC turned
on !

After looking in the BIOS, I found a power-management setting "Wake on
PME" which was enabled (now disabled !). Having looked up PME to mean
Power Management Event, I was wondering if there was something in the
modem, or router which was causing them to issue a PME signal ?

Can anyone confirm or dismiss this theory ?
Click to expand...

The PME signal is something that was added to the PCI bus. It is bussed,
meaning all PCI slots have access to it. Since the PCI bus is also used
for things like onboard Ethernet chips, it also means that an onboard
Ethernet chip has access too. (There may well be a similar mechanism
for PCI Express. The only reference I have there, is a connector pinout,
and I see a WAKE# pin on the connector.)

The second ingredient, is the chip in question would need a source of
standby power. PCI slots have some provision for standby power, and
definitely the onboard Ethernet chip is going to have it (it is a
common feature, to support Wake On LAN).

As for the waking functions of the Ethernet chip, there are two
types. Some chips support "wake on activity". In other words, if
they saw any packet, or if the PHY interface noticed a state change,
they might wake up. The second kind is "Magic Packet". In that case,
not just any packet will wake them. Specific data must be in the packet,
for that to happen.

http://en.wikipedia.org/wiki/Magic_packet (not the best article)

If you look in Windows, for the custom settings for the LAN chip,
you may find reference to the various waking options. If the chip
is well behaved, then disabling a couple of those settings, should
result in restful sleep :-)

Disabling PME in the BIOS, should make it more difficult for this
to happen (assuming that the BIOS interprets this literally as
an attempt to prevent any kind of wake from sleep activity). PME
terminates in some chip, like maybe the Southbridge, so I assume
a configuration bit would be present there, to either pay attention
or ignore PME, when the computer sleeps.

So there should be two levels of control available to you. BIOS and OS level.

Paul
 
HI guys,

I'm building up a mobo I inherited, MSI P4 (not sure of exact ID) with
an award BIOS. It's plugged into my (wireless) router, and the modem
is connected to my phone line.

Last couple of days, my wife has found it on, even though it was
switched off the night before. This is puzzling me. One thing which
may be a clue, is when I plugged the modem in, Sunday, the PC turned
on !

After looking in the BIOS, I found a power-management setting "Wake on
PME" which was enabled (now disabled !). Having looked up PME to mean
Power Management Event, I was wondering if there was something in the
modem, or router which was causing them to issue a PME signal ?

Can anyone confirm or dismiss this theory ?
Click to expand...

Yes the PME setting can be responsible for enabling another
PCI device to turn the system on. Had you turned your
router, switch, or another computer this system is networked
too off? If so, the NIC wake on link setting might have
caused it and is sometimes deactivated in the properties for
the nic in (windows, etc). If it's the (analog dialup?)
modem, have someone call that telephone # while system is
off to see if that turns it on. Regardless, unless there is
a separate cable from the modem to the system wake-on-ring
or lan header, turning off PME should have the correct
result... unless you needed PME enabled to turn on the
system with a different event.
 
HI guys,

I'm building up a mobo I inherited, MSI P4 (not sure of exact ID) with
an award BIOS. It's plugged into my (wireless) router, and the modem
is connected to my phone line.

Last couple of days, my wife has found it on, even though it was
switched off the night before. This is puzzling me. One thing which
may be a clue, is when I plugged the modem in, Sunday, the PC turned
on !

After looking in the BIOS, I found a power-management setting "Wake on
PME" which was enabled (now disabled !). Having looked up PME to mean
Power Management Event, I was wondering if there was something in the
modem, or router which was causing them to issue a PME signal ?

Can anyone confirm or dismiss this theory ?
Click to expand...

Yesterday, the PC didn't come on, so I'm assuming I was right. A
little more furtling in Windows showed me the modem had the "allow
this device to bring the computer on" flag checked. I've unchecked
that as well now.

Thanks for the (very informative) help
 
The Power Management tab on the NIC Properties has three tickboxes. The bottom tickbox is called 'Only allow management stations to wake the computer' which you must enable if you want to ensure your NIC only wakes if it receives a magic packet sent directly to the NIC.



If this setting is disabled, then any network activity sent to the NIC will wake it up, which might be any broadcast.



When off, the NIC has no IP stack so is only capable of receiving UDP packets, such as magic packets and other broadcasts.



If you want to use WOL then enable all BIOS and NIC settings including this tickbox. If you want to temporarily disable WOL on your NIC then disable all the NIC Power Management tab settings. These settings are easy to turn on and off using WMI scripts.



http://www.1e.com/download/whitepapers/BIOS%20Configuration%20Management%20v2-4.pdf



Ian
 
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