Periodic Buzzing noise with PC powered off

My computer is making a buzzing noise just audible enough to be heard across the room every once in a while. Like 4 times a day-ish. This noise happens despite the computer being turned off, although still plugged in to the power. Any ideas where the noise could be coming from and how to resolve the issue?

Do you turn the PC off or does it sleep/hibernate?

Are you using Windows 10 with Fast Boot enabled?

First guess = Power Supply

Second guess = Speakers, especially if a powered sub-woofer is plugged in which could have static build-up over time, simply unplug it from the back of the PC clean the plug with an anti-static wipe, allow to dry, and reinsert.

Seems to get allot of search engine hits with allot of people having the issue:

https://duckduckgo.com/?q=powered+off+PC+buzzing+noise

Third guess- you are in sleep (or hibernate) (or only turned the monitor off) and it's your AV (or the OS itself) checking, or updating files on, your hard drive while the computer is 'idle' and you are hearing the hard drive start up and spin.

I am powering off the PC not putting it into sleep. Fast startup is enabled. I have cleaned off the jack for the speakers so we will see if that does anything, however, I generally have my speakers turned off as well when the PC is powered down. If it were the power supply, what would be the cause/solution?

See here, then all the way at the bottom of the page there's related resources regarding a power supply making a buzzing sound:

http://www.tomshardware.com/forum/355146-28-buzzing-sound-coming-recently-built

As for the audio jack for the speakers, that can possibly happen due to static, or some other interference, etc. In the past I've had to unplug a 2.1 speaker system with a powered sub-woofer that was for my HDTV from the electrical outlet and plug it back in to stop the buzzing sound, eventually it became so annoying and loud I just replaced that speaker system.

If you have Fast Startup enabled then your machine is not truly powering off. It is sort of a hybrid sleep mode.

https://www.howtogeek.com/243901/the-pros-and-cons-of-windows-10s-fast-startup-mode/

Anyway, you have a few ideas what to troubleshoot now. Keep us in the loop :)

With Fast Startup enabled Windows 10 can be 'woken up' from shutdown to perform an action by a scheduled task. Usually this does not turn on the monitor.

Try taking a look in -

Control Panel > Administrative Tools > Event Viewer > Windows Logs > System

Check the time when you heard the buzzing to see if something (some scheduled task) is waking it.

Alternatively go to -

Control panel > Power options > Change plan settings > Change advanced power settings > Sleep > Allow wake up timers


and disable them.


That should rule out anything waking it up.

Alright I have disabled the wake up timers so we will see if the noise stops happening. I will update you guys if it worked or not.

Looks like disabling the wake up timers did not solve the issue. Any ideas of what I should try next?

with the PC power cable pulled out from the chassis, does the noise still occur?

Yep try what mta said. If that solves the problem it's highly possible that the fast startup option is contributing to this. Essentially fast boot/startup as was said earlier puts the system into a low power mode (akin to hibernate) and can allow the system to wake, the waking aspect doesn't seem to be the issue. So the issue is likely due to the system still being in a low power state (i.e it is still powered, compared to a traditional "slow startup" shutdown). Even physically plugged in without fast startup enabled there is going to be a small amount of power reaching the PSU, but with fast startup enabled, the power reaches past the PSU also flowing through the motherboard and to usb devices (I know this as I have a backlit gaming keypad which is powered solely via the usb from the computer, and if I shutdown my computer with fast startup enabled, it remains backlit, hence I don't have it enabled).

Essentially what mta suggests will eliminate the computer as the cause if it still occurs while unplugged, it could be coming from the power transformer if it's a laptop and/or, it could be the power-board (assuming you use one) etc.

Im at a complete loss now. I have unplugged the computer from power altogether and the noise still continued so I unplugged everything in that area from power completely just to test and the noise still happens a couple times a day just like before. Any thoughts on what it could be? Could speakers, the tower, or anything make a periodic buzzing noise when completely unplugged from a power outlet?

Perhaps it's the lighting in the room. Fluorescent lights bulbs/tubes can make a constant buzzing noise when they're about to burn out.

Very strange, as suggested it seems like it may be something other than the PC that is making the noise.

Do you have anything battery powered in or around that area that may be buzzing periodicaly to indicate a low battery?

Central heating pipes expanding/contracting?

One off the wall thought is that you may have a bug - a real one like a cricket, beetle, wasp, inside the PCs casing.

About the only thing to suggest now is to move the equipment elsewhere for a while to see if the noise is from the equipment or just from the area where the equipment was stood.

Moved every piece of electronic equipment to different locations in the house and the noise still comes from the corner that the computer was in. Still a complete mystery where the buzzing sound is coming from as there is nothing in the area left that would be able to make this type of noise and the buzzing is too soft to be coming through the wall from outside. I will have to just wait until one day it makes the noise while I am sitting right next to it so I can narrow down what the source is. Anyway, for now, we know its not the computer which was my main concern. Thanks for the help everyone!

Probably not, but:

https://www.nhs.uk/conditions/tinnitus/

It may be to faint to come through the wall from outside but it still may be coming from within the wall itself. Had an issue a while ago where I could hear a noise periodically (sounded like a small intermittent sprinkler or the noise water makes when someone holds their thumb over a hose to make the water disperse in a spray), turned out it was a pin-hole leak in a little water-pipe (approx 10mm diameter) running behind the plaster board, only found out when I noticed the carpet was wet in the area the sound could be heard from, but it took approx six months for that to happen and I had checked the carpet for dampness in that area prior. Anyway point being you may have insects of some kind living in the wall (it's more likely than in the computer case itself) but could also possibly be wiring or something else entirely, who knows maybe a trades person or previous owner accidentally dropped a pager or something down there once.

Anyway I'm sure the cause will reveal itself one day, and there will be some boring logical explanation, at least at the moment you can pretend it's ghosts or something else more interesting ;)

My 1st vote is for insects. Wood bees make a buzzing sound from within their nest tube. But their buzzing would be more constant. They leave fine sawdust when they drill out those nests.

2nd vote, less likely imho, would be the house wiring. Maybe a connection in a wall box getting loose. Or a breaker about to fail, such as a GFCI breaker.  It might be in the wall box itself or in the main service panel if it is nearby. 

Do the sounds occur at the same time each day? And do they coincide with any other electrical activity you know of?

Sounds like you are more or less finished with your investigation, but if you do find the cause please share it? <img alt=":)" data-emoticon="" height="20" src="<fileStore.core_Emoticons>/emoticons/default_smile.png" srcset="<fileStore.core_Emoticons>/emoticons/smile@2x.png 2x" title=":)" width="20"></p>