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Buzzing sound from PSU

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November 1, 2012 3:42:20 PM

howdy ya'll !(first timer, so sorry if I get things wrong).
I'm using a custombuilt PC (not assembled by me). I've had it running fine for about 2 or 3 years.
recently It got a bit of a whack from stuff falling onto it (no dents or anything and obviousley this has happened a lot before). after that a loud (moreso than normal) buzzing noise kind of like a motor came from the bottom-back end of my PC (what appears to be the Power supply, in it's own little box). I opened up the PC and used a clean paintbrush to clean the dust (and blew bits out) and the noise stopped.

after about 4 days away, it started making the noise again when I turned my pc on. I did the same again, blowing at the vents at the bottom-rear corner of my pc to try and clear whatever might be causing the noise and it seems to work.
every time I leave my pc off and come back to it after an hour the noise picks up again though.

could anyone give me some helpful advice? obviously I need toget some compressed air instead of using my mouth (blasphemy!), but compressed air is certainly not easy to come by and it isn't free either. do you guys think that would provide a longer-term solution than just clearing the dust off the vents (since this might not even be the cause of the problem anyway?).

P.S. my PSU is apparently "450W Quiet 80 PLUS Dual Rail PSU + 120mm Case Fan" according to the quote I got for the PC just before I ordered it. sorry it's not particularly helpful.

More about : buzzing sound psu

a b ) Power supply
November 1, 2012 5:08:01 PM

Could be the fan, but I have also seen the rubber "feet" get misplaced under PSU's and create a metal-on-metal vibration.

You should be able to remove the four screws that hold the PSU in place and take a look.

It may or may not be your problem, but it's easy to check, so worth a look.
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a b ) Power supply
November 1, 2012 5:25:55 PM

the buzz noise came from buzzing coil...

there's no cure of it, except opening the psu case, which is mean avoid your warranty..

if your psu still covered by warranty, return it..

for more days later, it will buzz louder and make headache..trust me, i'm an engineer..:D 
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Related resources
November 1, 2012 5:38:40 PM

I sorta wonder if you have a wire that got repositioned by the whack, and it's wanting to rest on top of a fan somewhere. Take a look at where your wires are with respect to fans, a wire in a fan will be pretty loud.
Aside from that, you may have cracked a bearing or something in a fan. You can unplug any fans in the computer (except the CPU), and try to figure out which.

If the place you bought it is an honest shop, they probably wouldn't charge you much to have it fixed (you should check up front though), and they could probably fix it while you are in the store.

My guess is it's just a fan somewhere; if it's the power supply fan, they will probably want to replace your power supply, I wouldn't consider that to be an unfair repair, as it can be dangerous to open a power supply (I've heard that it actually is not if you take proper precautions, however I wouldn't personally replace a PSU fan).

A new case fan should cost between 5$ and 20$ (depending on quality), a new CPU fan could be 10$ - 40$ (or more if it's a higher performance machine), a new PSU would be 20$ - 80$ (A good PSU will cost 50$ at least, a lot of the cheap ones don't really last, and can cause other problems, but as long as the shop will stand behind it, you should be fine). I would expect the work to be very inexpensive, 10 minutes to find the source of noise, 10 minutes to replace.

As for compressed air, you can buy it in a can for <5$ at WalMart, Radioshack, generic electronics mart, etc


edit: Forgot to say this one, but Quaddro may be right, the buzzing may also be a coil, and would require replacing some component (usually your PSU, but could be elsewhere). If the buzzing is clearly mechanical, it wouldn't be the coil; however if it sounds more like a high pitched whine, it's likely a coil.
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November 1, 2012 5:41:07 PM

That sort of sound can come from a PSU fan, depends how old the PSU is.
What you find is it makes a heck of a noise at first but you leave it for say 20 mins of running the system it goes away.
If that is the case, not saying it is. Its a case of the Psu fan having what we call a cheap copper bush and not a bearing fitted inside the fan. Bush type fans are packed with grease
and after time leak, and dry out. what you get then is a grinding type noise as the inner pin that hold the fan blades of assembly rub against the copper bush causing friction.
Anyway its a quick fix all you have to do it take the fan out of the PSU take the sicker of the back side center covering the access hole, it may be a rubber bung in there also.
There is a small plastic white or black C clip that sits in there.you can flip it out with a fine flat tip screwdriver. Don`t loose the clip. once removed a light pull of the fan blades with allow it to slide out. Thermal silicone grease is best to use, but you get away with using Vasaline.Pack it inside the bush slide the fan blade pin back in. Lay it on a table blade down get the C clip place on pin, use a bic with out the ink inside is the best way to re fit it. Make sure the C clip is stiing round the small groove on the center Fan blade Pin you will see that notch.
Job done god awful noise gone. If it the the cause.
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a b ) Power supply
November 1, 2012 5:44:19 PM

The only coil whine have experienced was from day-one with the only PSU that ever did it for me.
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November 1, 2012 6:03:06 PM

A solid jarring can break the glue holding the coil in place, allowing it to wiggle.
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November 3, 2012 9:26:34 AM

Thanks for the replies! I'm a bit anxious about opening the psu, but it does seem like there must be something in the wrong place. The sound isn't high pitched or anything and usually stops when I blow air at the pc vents, so don't think it'd be the coil problem.
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November 5, 2012 11:43:36 AM

I would advise you to buy a new PSU, rather than try to repair the one you have.

If you want to repair the PSU, do some research and learn how to do so safely. Unplug the PSU the day before you plan to work on it, then hold down your PC power button to discharge as much as you can that way. Let it sit for a day at least after that.

A new power supply is cheaper than a trip to the hospital. If you aren't confident in your abilities, try to find someone to repair the PSU for you, or buy a new one.
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November 5, 2012 11:52:19 AM

Hey all, more updates!
Just opened pay and cleaned around the seemingly clean fan. (I didn't die, but would rather not go through that again). There's still a sound despite the fan and ish the rest of the pay being clean. Occasionally using the tower in a horizontal position works (working now after the fan made a loud noise in the vertical position). But after I then the pc off and leave it for a while the noise comes back for this position too.

Did I mention that as long as there's no noise when the pc starts up everything is fine as long as its running? I've had the pc going for like 7+ hours as well.

This is really bizarre, I feel like the psu is deciding when it wants to work.


Oh and the label on it says the model number is:
FSP450-60APN (450w)

I'd really like to spend my money on something other than a new psi as well ^^
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