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Resolved Question

Possible Power Supply Failure

by RandomlyKnighted / November 11, 2013 10:12 PM PST

Occasionally, when I'm on my computer my computer will randomly reboot. I've also noticed that sometimes like this morning when I'm not using my computer I can hear the fan start spinning almost like it just rebooted except not as loud. This will go for 2-3 seconds then it will stop just as suddenly as it started. Could this be due to a power supply trying to fail? Is there anything else that might be cause symptoms such as these?

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Clarification Request
What is it?
by R. Proffitt Forum moderator / November 11, 2013 10:23 PM PST

To make a long lived machine, you want to get the PSU rating to about 50% (1/2) of the maximum power draw. PSUs age and lose capacity so to avoid issues you select the PSU at what sounds like overkill at the time.

There are other common causes such as lack of routine maintenance such as canned air on vents and heatsinks and at about 3 to 5 years you need to replace heatsink compound. These are trivial low cost (well under 10 buck) items so it remains a mystery why this work is often not done before the owner reloads the OS, does driver hunts or falls prey to registry and computer system cleaners.

But all this is moot as we can't tell what machine we are chatting about.

All Answers

Best Answer chosen by RandomlyKnighted

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Condition awareness
by Willy / November 11, 2013 10:38 PM PST

Where or what are the details of your PC in post? Heck, my car won't start, what do you think the mechanic is going to ask?

Now, if your PC actually has whirling fans when you don't touch the ON/OFF button, then that "suggests" you have either a very poor PSU that is getting compromised or the AC line its on is being spiked. Understand, typical PSU is logically turned-ON after pushing ON button, there is no real direct AC on/off switch but rather a control circuit showing a status of ON/OFF be processed, thus logic circuit. that's only 5V and that can be driven by over-voltage or spikes, etc.. the other half of this is the PSU is getting old or wasn't that good to begin with and easily pushed to an ON state. the reason the fan stop is because the spike or surge gets dissipated, used-up in other words and the capacitors are drained away. if you like, replace PSU with a better one higher wattage and amps and decent name brand applicable to your PC.

FYI-, I have this condition when I 1st plug-in my PC to AC line and immediately shows fan and LED lites, etc., for 2-3 secs. then remains OFF. It never turns-ON but awakes as it were. In that regard, check your bios for the "remote awake" feature of the LAN or network action most bios have. Disable and save upon exiting bios.

tada -----Willy Happy

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Condition Awareness
by RandomlyKnighted / November 12, 2013 3:11 AM PST
In reply to: Condition awareness

The fans always start whirling while the computer is on and without me toughing the power button. Based on your response I'm going to assume that the PSU is failing. I don't think it's the AC line as my monitor is plugged in right below and I've had no problems with it.

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Stuff happens
by Willy / November 12, 2013 4:06 AM PST
In reply to: Condition Awareness

You still didn't provide details of what PC you have. It maybe an oddball PC where the ON/OFF button actually hangs or stuck as it were. When walking by maybe enough to upset and start some errounously start-up. Again, it maybe that problem, but i have seen weird PC's act from a very poor ON/OFF conditon as I stated. The part of this concerns the monitor. The monitor itself is more power hungry and won't react from a minor power spike/surge though it could breakdown to include any electronic device.

Another example of power spikes, my answering machine will react and speak at odd times, during what I'm sure is a spike on the telco line. It too doesn't need much voltage and my phone being an old one really can clamp down from reacting to that, there's no logic circuit that gets tripped. This is only WAG on my part, but I've alot in tech repairs.

tada -----Willy Happy

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Stuff happens
by RandomlyKnighted / November 12, 2013 5:22 AM PST
In reply to: Stuff happens

I'm not at home at the moment, but if I remember right it's a Dell Optiplex 755 running Windows 7. It wasn't having this problem until about a week ago. I've had the computer for almost a year and a half.

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Do the PSU replacement
by Willy / November 13, 2013 12:06 AM PST
In reply to: Stuff happens

Dell and other OEM makers tend to build to what makes mode-XYZ able to work. I suggest that you get a similar sized PSU replacement of at least 100W over the current rating and of a decent name brand. You probably have at least 300W now installed -/+ 20W, so a 500W PSU isn't a bad idea. When it comes to power issues, it usually happens after some wear&tear has taken place. If you haven't yet, I also suggest you get a surge protector power strip and/or similar device to help reduce power issues. They're not that expensive but don't buy the cheapest one out there, though. Simple UPS or back-up bricks having some protection offer similar surge protection on top of possible UPS services, worth looking into.

I recommend you look into "bad caps" issue. Try http://www.badcaps.net for examples and inspect your mtrbd. for such. Understand a bad cap is anywhere caps are found.

tada -----Willy Happy

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Olbligatory Forum Message
by jon291279 / November 12, 2013 10:03 PM PST

This is just a message just to complete my final task.

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