Probably it is the temperature of the processor that makes your computer turn off unexpectedly. One piece of advice that I can give you is to check and clean your motherboard from dusts after that kindly check if your cpu cooler (heat sink) is well seated it happened to me before that my computer turns off without any notice and found out that the temperature went so high due to the heat sink that is not well seated.

In other words, electric short can cause the problem as well.
Unplug all cable, then clean all the inside.

Overheat or lack of enough power

Its a laptop, if it was a desktop I would feel more than comfortable pokin around the inside, but, haven't really moved in to laptops yet.

Got this thing that tells the temp of intel cpu's called CoreTemp (This link isn't mine), not real sure how accurate it is but at the moment its tellin me i'm about 155-170. So I can see the heat thing being a prob

Questions
Don't these things shutdown at about 210ish?
And, How to get around this?

what are these temps? c or f?

please use C

if you're using a desktop..make sure that you're heatsink to your processor is properly seated and there's enough thermal compound..and check processor fan also..

I had the same problem with my computer and end up being the power supply was overheating and would just shut off. I took off the cover and put a home fan towards the board not knowing exactly what was gong on until the power supply fan started making loud noises and then the power supply was fried. I tried to turn it back on and the computer started beeping. I looked it up and it was the power supply. Could also be the mother board, but in my case, the power supply. Taking the cover off and pointing a fan towards the motherboard, after making sure the dust is cleaned out, could work in the short term. Also check to make sure all your fans are in working order. See if there are patterns to when it shuts off. In my case when I played a video game it would shut off, but not when I was just using looking around on the web or using an office application. Since I have dual video cards, so the draw on the power supply would be greater for video games than a browser and it would create more heat through the power supply.

3 yrs later replying for archiving purposes

the laptop is an acer extenza 4620z

i eventually broke it down and found a dust bunny that wadded up to about the size of a gumball (monster lil thing)

over all i had to do this same procedure with same results about every 6mo.

i also perceive this as an acer design flaw between the fan and the heat-sink fins as there is very little room for debris to pass through

so if pc blacks out for no good reason at all, check heat-sinks and fans

Hi. 3 Years later then replied? Hmm, where have you been all this while. Lol

What you say about your last sentence is true. Mostely likely when your PC shut down for no apparent reason, it may be an overheating issue. Good to see you coming back to daniweb, smalls.