Magical mystery boot: Computer booting when lights turned on

Question

In my office we have four computers on a LAN: Two Ubuntu machines and two Vistas. Each is on its own power strip with surge protection, no UPS. The ADSL router is on a separate outlet. When we come in in the morning, before turning on the lights, it can be seen that the router has power, as do all four of the power strips. The computers can all be powered on without turning on the lights, and they have internet connection so I know that the router is powered on even before turning on the lights.

If one turns on the lights before booting any of the computers, then one of the Vista machines boots up when the lights come on. It will stay up even if the lights are then turned off. Thinking that maybe something is sending wake-on-lan I unplugged the network cable and tried again, sure enough the possessed Vista machine boot right up when the lights come on.

What might cause this? Should I document everything in a video to post to youtube to prove that the power strips are in fact powered even when the lights are off?

Answer 1

It can be an issue of the power supply being faulty and sending false power on signals when its power gets disturbed.

Is your computer turned off, or just hibernated? There was a similar issue mentioned here:

A program can tell Vista wait a certain period of time and then invoke some executable code at an address the program provides. An example is if you use a program like Microsoft's Outlook email client where you can set a reminder task for a future date and time. Outlook tells Vista to wait X amount of time and then execute some Outlook code. That Outlook code then displays your reminder.

But what happens if you put your computer to sleep or into hibernation? Well, before Vista you wouldn't get your reminder. Or maybe your anti-virus scan wouldn't happen. Or maybe Windows Update wouldn't run. Vista changed all that.

When Vista goes to sleep or into hibernation it first checks to see if there are any timers set to go off. If there is, it takes the next timer set to go off and sets an alarm in the platform hardware for that day and time. In the hardware this is typically an alarm that's part of the real time clock (RTC). Once Vista sets the RTC alarm it goes to sleep or into hibernation.

When the RTC alarm goes off your system turns on. Vista resumes and is notified of the alarm having gone off. Vista checks its timer list and executes the code associated with the timer that when off. When the code is done executing Vista will go back to sleep after two minutes of idle time.