For those that knows me well will know that I hate random lights on when I am trying to sleep and this is the tale of the motherboard that refused to turn off.
For the last few weeks I have been upgrading my PC and although it is not yet done (still need to get more RAM, new I/O panel and what not) the computer itself turns on and works fine although it a very loud device (the I/O panel has a temperature sensor on it to fix this).
With the upgrading now nearly being done and having it being a MUCH needed update I decided I might as well try the Final Fantasy XIV beta to see if it ran. It ran perfectly I really could not fault it (my review on Final Fantasy XIV will be the Playstation 3 version and will be published once the NDA expires) and after playing it with my brother for a while I decided to call it a night and go to bed.
So I shut down the computer, take out the plug and then walk over to the bed when I noticed something – the motherboard light was still on. Thinking that it is likely just some static or something I decided to nod off thinking little of it. A few hours later my brother wakes me up and says.
Me: “Eh, what you mean.”
Brother: “The light is on.”
Me: “Then turn it off.”
Brother: “I can’t.”
Me: “Just remove the power cord from the PC.”
Brother: “I have. It really will NOT turn off.”
So forcing myself out of bed with a somewhat confuse face I wonder over to my PC and my brother was right – the PC was still powered on and better yet the Serial ATA drive was still powered, the keyboard and mouse was still powered and even the USB wifi was still powered.
Yes, my computer was still on with no physical power cord being plugged in. Having now getting slightly worried that my upgraded PC may suddenly burst into flames we decided to have a look and there was nothing inside it that we could see that could explain why it is still powered up.
So to recap this computer has been unplugged for about 6-7 hours and the power light is still on and that I tried to remove the static. Well it seems after a while from poking around and trying to see what is wrong with it, the computer was still actually getting power from a very unlikely source and wait for it …. the USB port.
Now if you know anything about computers, you will know that a computer USB’s works in “usb host controller” mode. This means the computer will give power for any device that is connected to it and for some reason, some unknown reason the computer was being powered by a different device.
So having removed all USB cables I found the one that was doing it – the Onlap Monitor which still had a lot of battery power in it.
So there you have it. Spent all night in a half worried state my computer would suddenly set on fire when it was being powered by a monitor that had battery although I do not recall a USB host controller can even ACCEPT power from a different device.