Electrics flickered for just a few seconds pc turns off

Just had a bit of a scare with the pc. We had a flicker on the electricity all along the road which turned off the traffic lighes and the petrol stations pumps. We had the same yesterday and it used to occur quite frequently about four years ago but very rarely now.

Anyway it turned off my pc and when I pressed the power button to power on again it wouldn�t work! Checked the power supply light and it was on. So I took the side panel off and I could see that the motherboard reset button had the light on but the fans were not turning and neither were the HDDs�. Tested the USB ports with the laptop stand which has two fans and the USB ports had power. I could not understand how some parts had power but the HDD, the fans and the pc power button did not!

Very strange if you ask me on how some parts had power when the power button did not!

Any techies can explain how some parts of the pc have power and some don't even if the power button does not power on the pc??

Edited by deleted (Mon 02-Jul-18 22:41:32)

There are various feeds from the power supply on different rails. It could be that some of the rails stopped providing power and others continued.

Also, the motherboard itself can continue keeping some things alive whilst others appear turned off. The power button is a soft button so the motherboard can ignore it (which might look like it doesn't have power to it) whilst still powering other areas (ie some may have USB ports that stay powered even when "switched off").

Personally I would just unplug the power cord from the supply for half an hour and then try again.

Hi ian72,
I did eventually unplugged the power cord from the psu but just for a few seconds and plugged it back and everything went back to normal.

Today when I first powered on the pc Windows flashed a BSOD saying that it was collecting some information and that it would start the pc again. Which it did and all is working fine again.

These sudden electric faults some where outside our control do play havock with the pc.

If it's happening regularly, it might be worth spending a few quid on a UPS.

It does sound then as either a rail (or several) in the PSU went offline and needed a power cycle or the motherboard was receiving juice but had an error which meant it ignored the soft power switch (power switches haven't been hard switches for years and all the power switch does is send a message to the motherboard that you have pressed it, the motherboard then has to choose what it does with that information).

I have run sfc /scannow which did not find any violations,dism /online /cleanup-image /restorehealth completed successfully and chkdsk /scan Windows found no problems just to make sure all is well.

I am now looking to invest in a UPS as longedge suggest.

I have looked at several and CyberPower UPS with PFC Sinewave products which they say are the better option.
https://www.amazon.co.uk/CyberPower-CP900EPFCLCD-Bac...
I don't know what VA rating I should go for to protect a pc with 850 watt PSU plus the 57 watt monitor so that I can shut the pc properly in the event of a power cut.


Perhaps someone can enlighten me on the VA rating I should aim for. I would prefer a UPS which the battery can replaced.

If you are just concerned about shutting the PC down then the VA rating isn't really important. Any will keep the computer going long enough to shut it down. In fact most come with software that will do this automatically.

I can recommend APC equipment.

One word of warning - don't connect a laser printer to a UPS.

Thanks for you reply. I will get a UPS as a matter urgency.