PC won't turn on (PSU kaput?)

[Sumanji]

[EDIT]

Uh ok... literally seconds after posting this, I just powered it on and it worked?!

Must be that Hexus forum magic

Let's see how long it goes for, before blowing up

[/EDIT]





Hey,

I had my PC shipped over from the UK to the US, and I think the power supply has gone kaput! It's an auto-switching 100V-240V unit (Seasonic X750) so should work fine. However, when I turn the machine on it just repeatedly makes a clicking sound, and the CPU fan spins on for an instant:



I tried removing everything from the case and onto a wood panel, in case it was a grounding issue. With just the 24 pin and 8 pin connected to the motherboard the same thing happens.

I also tried powering up just the PSU (with the paperclip trick and one case fan connected), but nothing spins up at all when I do that - just the clicking sound.

So do you guys think that the PSU kicked it, or have I missed something else obvious?! The PC was working perfectly when I used it over Christmas, so I don't know how this could have happened... PSU is annoyingly just a couple of months out of warranty!

Any other suggestions please? If not, I'm going to try and pick up another PSU tomorrow and cross fingers that it works...!

Cheers,

Su

[peterb]

Must have been that dodgy US electricity supply!

[Sumanji]

Yeah mate it's not great... and don't get me started on the plug sockets!!

[DDY]

Classic symptoms of a failing power supply, I've experienced exactly the same symptoms from both good and bad brands.

[Sumanji]

That's disconcerting... what makes you say that, DDY?

It's worth noting that between now and last Christmas, the PC has sat unused. And then between that Christmas (2014) and July 2013, it had been sat dormant as well...!

[DDY]

In a bit more detail; I've replaced and repaired a number of bad power supplies that had exactly the same or similar symptoms.

Sometimes the machine would eventually power up after a few 'attempts', other times the hard power switch on the back needs to be toggled for another go. The faults can be intermittent and progressive, happening at first once or a few times a month, to happening on every power up, eventually to a point where the power supply can't power up the machine up at all. Though once powered up, the machine operates normally.

Pulling apart these power supplies and having a basic poke about, I've found that possibly;

a) The 5v stand-by rail is dodgy and the motherboard can't start up,

b) The motherboard doesn't receive a power OK signal for whatever reason so the motherboard shuts off and attempts another start up,

c) The power supply is responding to a fault by power cycling, or maybe undergoing a fault induced oscillation

Considering that you've done the paper clip thing, from what I gather your power supply might be doing a c).

[Sumanji]

Hmm, ok... what would you recommend that I do? I guess I can't really do anything apart from watch and wait right?

Unless there is a risk it could blow and take out my machine - would you say I should replace the PSU preemptively

I've gamed on it for a couple of hours and it was fine (DoDs, so not really maxing out, but under load for sure).

Cheers,

Su

[DDY]

If that were my system, I'd feel happier replacing the PSU, but then again the machines that I've just left alone haven't blown up, at worst the PSU needed replacing. YMMV of course.

My theory is the capacitors have naturally aged and are struggling to cope with the start up surge, especially considering that the system has sat unused for some time. Capacitors lose some of their capacity if sat unused, some of that capacity is restored over time once it's in use again, but will never regain losses associated with use and aging.

[shaithis]

It's a seasonic unit.

Personally I'd wait until it becomes a problem and then replace it (for no other reason than saving money!).

I recently had the exact same thing with one of my ESX hosts and a 300W seasonic PSU. Eventually it took about 20 attempts to turn on, at that point I replaced it and now it turns on every time. It might be worth replacing sooner-rather-than-later, especially as your in the US now and the price won't look so bad

[Thorsson]

...when I turn the machine on it just repeatedly makes a clicking sound, and the CPU fan spins on for an instant

That's a classic symptom of a short, e.g. a loose screw between the mobo and the case, but lots of other possibilities.

[Sumanji]

That's a classic symptom of a short, e.g. a loose screw between the mobo and the case, but lots of other possibilities.

Yeah, that's what I thought initially, hence taking the whole machine apart and trying to power on the mobo placed on an old wooden chopping board it still didn't work at that point though.

Could it have been a short inside the PSU?! Maybe all the jiggling about dislodged something

[DDY]

Could it have been a short inside the PSU?! Maybe all the jiggling about dislodged something

It's possible but I doubt it, at least a short within the PSU.

Modern PC power supplies have short circuit protection, this internally 'disconnects' the power input if a short is detected. The power supply then will only power up again after the power input has been physically disconnected, in this case by pulling the plug or toggling the power switch on the rear. Usually, short circuited supplies wouldn't even perceptibly power up, if it does, it will only do so for a very short moment and then appear to be completely dead, until of course the SCP is reset by disconnecting and reconnecting the power supply, though preferably after removing the short!

A short outside the power supply is another matter, especially if it's to do with the motherboard!