Computer shut off abruptly, won't turn back on

Delduwath

A couple of days ago, my computer shut off abruptly in the middle of normal operations (I wasn't doing anything out of the ordinary on it) and wouldn't turn on when I pressed the power button. There was just no reaction at all.

Last night, I performed the paperclip test on the PSU. The result is this:
When I turn off the PSU, unplug the power cable, disconnect the PSU from everything, insert the paperclip, plug the power cable back in, and turn on the PSU, the PSU fan starts to spin.
If I then turn the PSU off and back on again, the fan does not spin.
If I unplug the power cable, re-plug it, and then turn the PSU back on, the fan will start to spin.

Is that as expected? I was hoping that it was just a fried PSU, as that's trivial to replace, but it seems like maybe the PSU's fine? In which case I guess the next step is testing the motherboard, but to be frank I'm not 100% sure how to go about doing it. When the computer is wired up for normal operations (meaning, the PSU's plugged into everything, etc), the motherboard light that indicates whether or not there's stand-by power is a steady red (indicating that yes, there is stand-by power), and all the ostentatious motherboard lighting effects are on, but there's no reaction when I hit the power button: PSU fan doesn't spin, no activity from the harddrives, the CPU cooler fan doesn't spin, there's no POST beep from the speaker, etc.

Could anyone offer some advise on where to go from here?

For reference, my PSU is this 6-year-old veteran, and my motherboard is this one. I built the computer last year (the PSU I cannibalized from my previous build), and haven't noticed any hardware issues until this sudden shut-down.

Thank you!

wunderbar

if your PSU is 6 years old and the rest of the parts in the PC is a year old, it's likely that it is the PSU. If you have another one to test with, try it. If you don't, I'd recommend buying another PSU, and returning it if the PSU doesn't end up being the issue.

Delduwath

I was leaning in the same direction, paperclip or no. Thank you for validating what I was already thinking (which is how I know that you are Right and Correct)!

Mugsley

I had a similar problem, and my PSU is a 10-year old PC Power & Cooling juggernaut. It turned out my video card had fried while I was away to see family for the weekend -- with no visual cues as to the culprit.

Since the PSU appears to be sending good power to the motherboard, try disconnecting the power to your video card and connect your monitor to the onboard video. Similarly, disconnect other components one at a time and see if the computer boots up, if it isn't the video card.

If you have access to a multimeter, you can use the paperclip jumper to turn on the PSU and check you're getting good power everywhere.

Delduwath

That's the thing, I'm not actually clear on whether or not it's sending good power to the motherboard. I tried powering the computer on with only the motherboard hooked up to the PSU, and got absolutely no reaction (no POST beep, no CPU fan spinning, nothing), so I'm not sure it's the video card in this case.

Mugsley

Hm, yeah. I was mostly making sure you weren't tossing away a potentially good PSU and that your problem wasn't elsewhere. I know the PSU is old, but I recommend you reach out to Corsair and see if they are willing to work with you. You can also message /u/GloriousGe0rge on Reddit and he may be able to point you at the right people.

Of course, that's all assuming you are willing to wait for the dialog/shipping from Corsair to address the problem.