Computer shutting down and starting up by itself

[Capn Bloggs]

I have a weird problem. One of my PCs sometimes won't start when I press the button (there is power to the motherboard; I can see the little green light on it) but then after a few minutes it springs to life. Other times, it will start but then stop by itself, then restart some time later. I don't think it's temperature-related.

I'm thinking power supply or motherboard, maybe RAM, but before I start on a "change this change that" maintenance task (can't even MEL this one!) I would be grateful for any ideas from the floor.

Thanks!

[NutLoose]

It might be worth leaving it unplugged for a bit then unplugging and replugging everything in again such as memory, power cables, cards etc

[NutLoose]

Is there any numbers shown on the motherboard or coloured lights as they often refer to the fault, you can normally get the code reader on the cards manufacturers website.

[waito]

Fast guessing:

Power Suppy, it's also one of the cheaper parts.
Maybe the Windows Tool "Event Viewer" gives a hint (but unlikely). Check Computer Time roughly in sync with your clock. Note time of next shutdown. Thereafter, open Event Viewer and search if a hardware component is suspicious.

[Capn Bloggs]

Thanks all, it was the power supply. Fortunately (and by chance) I could replicate the shutdown by plugging in my wifi dongle. There was a muffled click when the machine died each time, and the power button wouldn't respond for a restart unless I disconnected and reconnected the power lead.

[Loose rivets]

I once replace the electrolytics around the CPU because of uninvited restarts. It wasn't the easiest of jobs.

[Capn Bloggs]

I once replace the electrolytics around the CPU because of uninvited restarts. It wasn't the easiest of jobs.
Yikes! Definitely a "Repair by Replacement" job, that one!

[Loose rivets]

Yes, and I wanted to over-spec the capacitors. As a result, they were about 10% larger in diameter. I could do this by leaving the wires longer and shoving the c's over here and there. It worked for years.

Got the clue from someone on here.

[netstruggler]

I once replace the electrolytics around the CPU because of uninvited restarts. It wasn't the easiest of jobs.

The increasingly common 'bulging' capacitor issue?

I've just replaced a couple of electrolytics in my bathroom extractor fan to fix erratic behaviour as it neared the end of the timer interval. I've also fixed a computer monitor that way when it became difficult to turn on and off.

At least it's easy to see where the problem is.