Question PC doesn't power on after a power outage in my street ?

[waynemca]

My old (2009) PC with an ASUS P5Q SE Plus motherboard has normally been up and running for years, acting as a server.

In the past, when residential power outages occur, I have had no problem powering the machine up again.

A few days ago, we had a street-wide power outage for about 8 hours, and when the power came back again, I could not power up the PC.

The motherboard's green power LED is on, but nothing happens when I press the front panel power button. No fans or lights come on either.

There are no beeps from the speaker to signal any BIOS POST faults.

The PSU (Cooler Master 650W Bronze) passes the test suggested by the vendor (https://landing.coolermaster.com/faq/how-to-test-a-power-supply/) and disconnected from the mobo - this causes the fans, lights and peripherals to fire up ok suggesting that the PSU is ok.

I've disconnected the power cable from the PSU, removed the CMOS battery and used the "clear CMOS" jumper. I'm going to wait a decent amount of time to see if that fixes it.

I'm now starting to worry that the AC power conditions spiked when the residential power came back up. Has anyone any thoughts or have experienced this before?

Thanks in advance for any advice.

Regards,
Wayne

 

[Ralston18]

Update your post to include full system hardware specs and OS information.

= = = =

The "paperclip" test is very basic.

Do you have a multimeter and know how to use it? Or know someone who does?

FYI:

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Not a full test because the PSU is not under load.

However, any voltages out of tolerance indicate a faltering or failing PSU.

If testing is not possible then the next option is to swap in another known working PSU. Be sure to use only the cables that come with the substitute PSU.

 

[bill001g]

More than likely some issue with the motherboard if the power supply really is good.

A power spike generally can not pass through the power supply without it also killing the power supply but it doesn't really matter now. In the future you want to run a UPS to reduce issue. Something like a lighting strike can still damage a computer on a UPS.

What you now want to do is see if the motherboard is connecting the 2 pins you tested with a paper clip.

So first check with a multimeter that pin 9 is 5 volts as soon as the power switch on the power supply is turned on. This is the power that the motherboard uses before it technically it powered on. Most modern motherboards have some kind of led that comes on as soon this is on....one of mine has a massive number that I can't turn off...only change the color.

What you now want to do is see if pin 16 which should be a green wire is connected to ground when you push the on switch. This is hard to test mostly because it must be done while the cable is connected to the computer and in many cases it is hard to get your hands and probes into the top of the connectors where you can measure things. You might want to test outside the case but it all depends which is easier.

In could also be as simple as the front panel switch is broken so you could remove it and quickly short the 2 pins it connects to see if the machine comes on.

 

[Grobe]

First: Was there any other equipment other than your computer taking damage from the power outlet ?

Also - a mobo from 2009 - 15 years of age is actually way past what I'd consider expected life time, and wouldn't be surprised that a power outage is enough to get it to "tip over".

 

[waynemca]

Update your post to include full system hardware specs and OS information.

= = = =

The "paperclip" test is very basic.

Do you have a multimeter and know how to use it? Or know someone who does?

FYI:

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Not a full test because the PSU is not under load.

However, any voltages out of tolerance indicate a faltering or failing PSU.

If testing is not possible then the next option is to swap in another known working PSU. Be sure to use only the cables that come with the substitute PSU.

As this is a pre-boot problem, I didn't add the HW specs or OS info since it did not seem relevant to the issue.

The voltages are all present on the EATXPWR plug from the PSU without load (when the 'paperclip' is inserted).

When I plug the connector back into the motherboard (leaving the paper clip inserted) then no voltages are present. The PSON# signal is grounded (TRUE) by the paperclip, but the PSU doesn't produce any output.

I want to swap out the PSU as the simplest action, but will have to purchase a new one to try, and it's doubtful the vendor will allow return/refund

 

[waynemca]

More than likely some issue with the motherboard if the power supply really is good.

A power spike generally can not pass through the power supply without it also killing the power supply but it doesn't really matter now. In the future you want to run a UPS to reduce issue. Something like a lighting strike can still damage a computer on a UPS.

What you now want to do is see if the motherboard is connecting the 2 pins you tested with a paper clip.

So first check with a multimeter that pin 9 is 5 volts as soon as the power switch on the power supply is turned on. This is the power that the motherboard uses before it technically it powered on. Most modern motherboards have some kind of led that comes on as soon this is on....one of mine has a massive number that I can't turn off...only change the color.

What you now want to do is see if pin 16 which should be a green wire is connected to ground when you push the on switch. This is hard to test mostly because it must be done while the cable is connected to the computer and in many cases it is hard to get your hands and probes into the top of the connectors where you can measure things. You might want to test outside the case but it all depends which is easier.

In could also be as simple as the front panel switch is broken so you could remove it and quickly short the 2 pins it connects to see if the machine comes on.

Thank you for replying.

Pin 9 (+5V Standby) is at 5V when the PSU is switched on/disconnected from mobo/paperclip inserted. So that's encouraging. The LED on the mobo lights up.

Pin 16 (PSON#) reads 0V with or without the paperclip, which is a worry. I did try shorting the front panel power button to simulate the button 'press' but it was a no-go too.

So I think I've got either a motherboard or PSU failure with no satisfactory way of isolating which is the cause without buying replacements to test.
I can't afford to do that presently, so I'll sit tight for the time being.

 

[waynemca]

First: Was there any other equipment other than your computer taking damage from the power outlet ?

Also - a mobo from 2009 - 15 years of age is actually way past what I'd consider expected life time, and wouldn't be surprised that a power outage is enough to get it to "tip over".

No other equipment affected as far as I can see. Two printers and the monitor were on the same power board (which supposedly has surge protection) and they are fine.

Perhaps as you say, the motherboard's age could likely contribute to its failure. The PSU was replaced about 4 years ago, but it still might be the culprit.

 

[Ralston18]

Re:

"As this is a pre-boot problem, I didn't add the HW specs or OS info since it did not seem relevant to the issue."

May or may not be relevant but there is nothing to be gained by excluding what is often helpful information.

For example, the build may require more wattage either directly or beyond what that old 650 watt PSU can provide/support.

Also:

"Two printers and the monitor were on the same power board (which supposedly has surge protection) and they are fine."

It is good that they are fine. However, surge protection (Joules) is cumulative., The results of another outage or strike may not be so fortunate.

Find out if there is indeed surge protection and, if so, what is the surge protectors' rating. Age/condition?

Electricity will find paths one way or another. Outages include surges especially when power returns....

The motherboard and PSU are both potential culprits. Consider that they may be victims. Eventually one or the other (or both) may be found to be at fault. And subsequently replaced.

And then there is another outage or surge.

Keep the bigger picture in mind.

 

[waynemca]

Re:

"As this is a pre-boot problem, I didn't add the HW specs or OS info since it did not seem relevant to the issue."

May or may not be relevant but there is nothing to be gained by excluding what is often helpful information.

For example, the build may require more wattage either directly or beyond what that old 650 watt PSU can provide/support.

Also:

"Two printers and the monitor were on the same power board (which supposedly has surge protection) and they are fine."

It is good that they are fine. However, surge protection (Joules) is cumulative., The results of another outage or strike may not be so fortunate.

Find out if there is indeed surge protection and, if so, what is the surge protectors' rating. Age/condition?

Electricity will find paths one way or another. Outages include surges especially when power returns....

The motherboard and PSU are both potential culprits. Consider that they may be victims. Eventually one or the other (or both) may be found to be at fault. And subsequently replaced.

And then there is another outage or surge.

Keep the bigger picture in mind.

Good point - I'll try grabbing another PSU.

Thanks to all for your replies.