PC turning itself on!

A friend came to me today and related how he was sitting in his kitchen when he heard strange sounds from another room. Upon entering that room he discovered that his computer had turned itself on! The LED light was pulsing but the screen was blank, with a whirring sound coming from the main box. Does this phenomen sound familiar to anyone? His computer is about two years old, with WinXP SP2. Thank you.

By the way, he lives on his own

 

Hi Lugwalker,
Has it been working OK since then?

It is probably a BIOS setting. There are settings like "After power failure: restart "; "Wake on LAN "; "Wake on ring ". When I first got this computer it was defaulted to "Wake on ring ", I have my phone connected to the modem so every time the phone rang the computer started .

Matt

 

I'm afraid it hasn't worked since this happened, Matt. He has to unplug the machine to turn it off. It'd dead, as far as he's concerned (even with the LED light working and the machine making strange noises).

 

Sources of noise from the case (main box) are most likely fans or faulty drives. He can position the case so that he can inspect the fan/s at the back of the case. Use a flashlight and see if they are spinning freely and not the source of the noise. If there is a problem with a drive the drive light will stay on constantly, so check for the HDD or floppy drive LED staying on (I don't think it would happen that way with a faulty optical drive). If it seems to be a drive, I would reseat the connections before replacing it and there may be a small chance that the data/ribbon cable is faulty.
After that you would need to open the case and check the fans inside with the machine running, like the CPU fan, the graphics card fan, the chipset fan. Check for build-up of dust in the heatsinks under the fans, the fans can be removed and the dust cleaned out of the fins of the heatsinks, but do not remove the heatsink from the processor chip.

Since it has done this strange startup, I might suspect the power supply. The power supply has a large fan (next to where you connect the mains power cable). If that fan is faulty it can be replaced, otherwise a problem with the power supply means getting the power supply (PSU) itself replaced. Most power supplys are standard, a minority require manufacturer replacement.
(BTW, check that the mains power cable is fully seated).

Let us know what you find.

Matt

 

Thanks for your very detailed post, Matt. My friend tells me that he has found the receipt for his computer purchase and, good news, he's still under guarantee. He's leaving it in with the retailer this weekend. When it's returned I'll report back to yourselves. Thanks again