PSU internal component failing ?

  johndrew 10:03 22 Nov 11

Or something else?

Recently when switching on the PC at the mains I have noticed a high pitched noise - not fan like, more like an oscillator whine. Additionally it takes a couple of seconds (noticeable time) before I can press the start button and get a green power light - this used to be instantaneous (almost) previously.

When turning the PC off (after Windows has closed) the whine is still present until mains power is turned off then it raises slightly in pitch and decreases to nothing (inaudible). I appears to me that it could be related to a capacitor discharging after power being removed.

The PC is functioning normally in other respects and the noise, assuming it is constantly present, is masked by fans/drives during operation. It is only when fans/drives are not on that I hear it.

Does anyone have any experience/knowledge of similar noises which may indicate a fault?

Many thanks in anticipation for any advice.

  gengiscant 10:36 22 Nov 11

Can you pinpoint the noise to the PSU?

  bjh 10:54 22 Nov 11

Sounds like capacitor whine. It's a known problem. You could replace the PSU if you are sure it is there. Seriously, don't open up a PSU, even when disconnected from the power. They can be lethal!

  johndrew 10:57 22 Nov 11

Thanks for coming back.

The exact location is not clear; this is the problem. My hearing isn't what it was (some years ago) and although it sounds to be coming from the back of the PC, where the PSU is located, it is also close to other items on the motherboard.

I think I can rule out RAM and items close to the front though.

  gengiscant 11:01 22 Nov 11

Disconnect every power connection bar the motherboard and CPU fan,hopefully you should hear if the whine is coming from the PSU or not.

  Graphicool1 11:02 22 Nov 11

Hi johndrew

I've had similar problems with PC's in the past. Locating the origin of the sound, it can be difficult. However, here are two thing's I have used with success.

The best thing, (if you have one to hand) is a long skinny desk mic. Remove the side of your PC and move the mic around inside.

No mic? Then take a sheet of paper, roll it up, making a long, thin, cone shaped tube. Put the large end to your ear and move the other end around inside the PC.

I know it sound a bit like an episode of 'Blue Peter' but, they've both worked for me, at various times and let's face it, it's results that count.

  johndrew 11:06 22 Nov 11

Thanks bjh.

I accept the PSU isn't one of the best in the world, it's a Hiper 480W unit, but given that I am looking to replace the PC (probably after Christmas) I was looking for a bit of confidence that a replacement PSU or something else wasn't on the cards in the very near future.

If it is capacitor whine am I likely to see a sudden failure?

  johndrew 11:09 22 Nov 11


No mic, but I have paper.

I shall try that. A bit of plastic tube didn't work but the paper tube diameter can be controlled better.

  johndrew 10:36 23 Nov 11

Sorry to have been so long in coming back with any results but it took some time to do as was suggested.

With only power on to the PSU but with all other parts normally connected I used various items from rolled paper to plastic pipe as a stethoscope facility. The whine is definitely to the rear (my wife also agrees this) and I have a level of confidence that it is from the PSU.

I did move my hearing trumpets around to see if I could get a definite difference top to bottom of the case but it was difficult to gain straight access vertically - the noise seems to be projected downward from the bottom (fan grill area) of the PSU.

Can anyone now give a better idea as to my question, please. Specifically, if it is capacitor whine am I likely to see a sudden failure?

  bjh 10:48 23 Nov 11

Two schools of thought - one that it is indicative of a failure, the other that it will not cause a problem. Both seem right in different circumstances. I know that's not helpful, but... In general, whine doesn't lead to failure, unless it gets so loud and maddening that you hit the damn thing with a hammer.

You say you are going to replace the PC after Christmas. Well, then I would do nothing to this PC except ensure I had good backups. It's conceivable the PSU will fail. It's just conceivable that, with the PSU blowing, the motherboard will also fail... but unlikely, very unlikely. If it fails, and you are intending to get a new machine soon, just but a cheap PSU from Ebuyer or one of the other cheap retailers. I wouldn't bother to replace it earlier.

Just to repeat, please don't open the PSU, as there are some naty voltages inside. However, there's one last possibility... the PSU fan. That might be gummed up. Can you see it going round smoothly? If you have WD40 with a thin red tube for squirting, the smallest, smallest drop might help. I wouldn't recommend this unless the noise is dreadfully irritating, and I wouldn't do it on fans elsewhere.

  gengiscant 10:53 23 Nov 11

If you do not mind getting your hands dirty,so to speak,then you can use a method I have used and in fact still do when I need to test components and I do not have a spare mobo kicking about. I have found a video which makes the process so much easier to follow. Test PSU. Using this method will at least pinpoint the noise or not to the PSU.

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