Ghost Startup

Not sure what topic this would go under, but any way...

My wife's computer is randomly powering up with no human interaction of any kind. (Kind of funny in a way because some people can't start their computer at all. )
I have checked the BIOS and the Ringer/Lan Wakeup is disabled. The Wakeup when any key depressed is enabled, but no one is near the computer when it does start.

We're behind a router with all ports closed, so it can't be someone "phoning home" so to speak.
Can't be a virus/Trojan because the computer is off and I can not see a virus/Trojan being able to do that.
As with the virus/Trojan, I can't see Windows starting the computer at cold boot.
I thought it might be a faulty keyboard (Wakeup when any key depressed) but the keyboard has no problems in Windows at all.
As with the keyboard, there might be a very slight problem with the motherboard, but no other problem at all other than this. And this not a major thing in my book.

And it's totally random. It can be days or weeks in between of this "ghost" powering up.

Anyone has any crazy idea why this is happening other than keyboard/motherboard?

Thanks.

 

Laptop or desktop? I have a laptop that behaves as you describe when off the mains.

 

Desktop.

I was thinking it was the router DHCP distributing IP addresses to the LAN network, but that is not the case.
It renews once a week, but the LAN network has static IP addresses.

It turned on again today at 10am. It seems to be in the mornings that I know of.

 

What mode is it in when shutdown. Are all case LED's and PSU fan off, and is there any power evident on the keyboard and/or mouse (if optical with a lit LED)?
Could it be a faulty (intermittent) front power switch? Maybe an intermittent PSU problem. Unplug from the mains for several minutes to fully drain the PSU capacitors. What about a BIOS update (if available).

 

Mode is hibernation.
Case LED's and all fan's are off.
Keyboard number lock is on. Is this common with ATX's? Mine does the same thing. If it's not common, must be how the motherboard is made to respond to Wakeup when any key is depressed.
It could it be a faulty front power switch or an intermittent PSU problem. But usually the computer is on all day without any problems.

I just noticed this when the computer has been off during the day when I'm home. I have no idea if it starts during the night. I'll probably write a simple DOS command and output the time in a file when the computer starts Windows and put that in the Startup folder.

 

Ah - hibernation is lots more 'awake' than having it shut down would.

How about the network card settings? I have mine unchecked in this picture and a different brand of NIC may look different but should have something similar.

 

Well... I was able to determine that it was a 'Windows XP Home' program starting the computer from a cold boot. It was Windows Backup utility.
How it is able to do this baffles me.

 

You probably have the same (mistaken) idea that most folks seem to about PCs and power. When you turn it "off" you have simply put it to sleep. Standby, hibernation, off, are all simply stages of sleep if you have ACPI which most newer machines do.

If you want to know more, This is a good article although sorta techie in spots.