Need advice about possible hardware problem in computer.

For the past week, my computer has irratically re-booted itself. It’s happened when there was a lot of load on the system and while it was idling. I thought it was a software problem and have since run just about every diagnostic tool I can think of.
This morning, I woke up and realized a fuse had blown. I replaced the fuse and heard the familiar sound of of a short circuit, followed by a faint but distinct smell. Using my nose, I sniffed my way to the computer, and sure enough, it was the source of the blown fuse. Turning the main switch on the back of the computer off, replacing the fuse and throwing the switch again gave me another blown fuse. I can now only conclude there’s something unhealthy in the computer. My first guess would be the power supply, which I will check later today. However, if it’s not the power supply, I need suggestions about what else to check.

I have an Antec Sonata II chassi with a 400W power supply.

Which fuse are we talking about?

If it’s the fuse in the power plug itself, or the one in the Power Supply Unit, then it sounds like a short (or some other fault) inside the PSU. Anything downstream of that shouldn’t be blowing a fuse.
It could just be a fault in the mains cable, or even the wall outlet into which you have it plugged - those are probably cheaper and easier things to test than the PSU.

I would strongly advise against trying to repair the PSU though - it’s dangerous if you don’t know what you’re doing and replacements aren’t all that expensive.

The main power fuse for the living room, not the fuse inside the PSU. Swedan doesn’t have the same system as the U.K. (fuses at each connection point) but rather a main panel with fuses for different sectors of a home.
The power outlet is grounded.

OK, I would test in this general order:

-Test some other appliance plugged into that socket
-Visually inspect the mains power cable for damage (unplug it first)
-Try the computer with a different power cable
-Replace the PSU

BTW, UK house wiring typically has a distribution panel with fuses or breakers - which sounds the same as your setup - additionaly with fuses inside the mains plugs (as well as any further fuses that may exist inside the appliances themselves).

It is, of course, possible that none of the above will remedy the problem - the symptoms you describe from when the computer was still working sound a bit like overheating due to a failed CPU fan, but in my experience, faults with components of the actual computer (such as CPU, motherboard, RAM, hard drives) don’t usually cause external fuses to blow.

If your computer is blowing fuses, then it is most likely a short in the power supply. Power supplies are cheap. Get a new one and hope that your motherboard isn’t cooked.

That’s what I was thinking of - the fuses in the plugs.

Anyway, I used the checklist provided by Mangetout (thanks) and it was indeed the PSU. They’re NOT cheap, BTW: $150 for an Antec 500w.
THE CPU fan is working properly and I’ve had the chassi for two years, and haven’t put unreasonable strain of it lately. So it probably just wore out.

Thanks guys. If a mod happens to walk by, feel free to close.

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Closed at the OP’s request.

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