Hi!

Recently my computer has been switching off for no reason. Not shutting down, just turning off like a light switch.

I have no idea how I'd even start to diagnose this problem. Any suggestions? A log file somewhere I should look at?

I'm running Arch on a Toshiba A200 laptop.
It's not overheating.

You might look for /var/log/acpid or /var/log/kernel or /var/log/messages for starters. But if the machine is turning off like a light switch out of the blue, the event(s) leading up to this may not be logged, especially if it's a hardware or power supply problem - the kernel may not have time to log anything, if there's even something to log.

Is the machine running on battery or AC when this happens?

If running on AC, and the computer's battery is defective or not installed, AND if the AC power cord or conenctor is damaged or worn out, jiggling the wires might make the machine turn off -- does it?

Does it happen with any regularity, or totally random time interval? Are you always doing some particular task or application when this happens?

Does it turn back on normally after this happens? Like, the power button turns it back on?

How do you know it is not overheating? Can you hear the fan running? Is the fan clear of dust, and spinning freely?

Thanks GrapefruiTgirl

I checked all those logs but couldn't find anything suspicious so I guess whatever's happening isn't being logged.
The laptop usually runs on AC power but I can unplug it and keep using it so the battery is installed and working.
It seems to happen at totally random times, even if I'm not using it, it turns back on fine afterwards though.

It does overheat sometimes but I can tell when its at risk of overheating because its usually on my lap and it gets hot. Plus when it overheats it drops back to a text terminal and gives me a message about critical temperature being reached, rather than switching off instantly. It also only tends to overheat during hot weather or when I'm making it do some hard labor.

I'm guessing since nothing is being logged this is a hardware issue. I may try reformatting/reinstalling and if that does nothing start saving up for a new laptop.

Moved: This thread is more suitable in Linux-Laptop and Netbook and has been moved accordingly to help your thread/question get the exposure it deserves.

I'm not sure what to suggest next -- there should be other logs in the /var/log directory, particularly "syslog" -- which you can also check.

It might be that sometimes, the thing gets hot and does an orderly shutdown (and you see the temperature messages on the console) and other times, it just shuts down rapidly without the messages.

I have no idea what options there might be in your BIOS for temperature & fan control, if there are any at all, but it'd be worth a look; if there's options for setting the tripping temperature at which the machine turns off, evaluate if that setting is a reasonable number, and tell us what options there are for the action taken when the temp reaches the critical level.

Some computers (my roommates AMD desktop for example) will have a big red message in the BIOS or on the boot screen at power-up, telling the user that the machine last shut down due to temperature.

If you have not yet, install some sort of system monitoring tool, like gkrellm for example (or on KDE, ksysguard would work), and keep it running on your desktop. Examine the output of the tool frequently and watch the temperature. This should give an indication if the temperature is contributing to the problem or not.

Good luck, and keep us posted of anything you discover.