What is this weird sound coming from my PC?!?!?

davidstone28 · Post by **davidstone28** » Thu Oct 07, 2004 6:15 am

It makes a "sscheet sscheeet sscheeet ssccheet [pause] sscheeet sscheeet sscheeet sscheeeet" sound.

And it sounds as if its come directly from the motherboard / CPU / graphics card area (not from HDDs, PSUS or optical drives).

It's the just weirdest thing I have ever heard.

It's not loud, in fact when I put the side panel back on my case, I can't hear it, but it's just weird. Never noticed it before.

Does anyone have any idea as to what might be causing it?

(BTW, all fans are switched off - absolutely everything - CPU, case, GPU, PSU etc).

Wraith · Post by **Wraith** » Thu Oct 07, 2004 6:24 am

Does it happen intermittently? Or does it happen the whole time you have it turned on?

davidstone28 · Post by **davidstone28** » Thu Oct 07, 2004 6:36 am

Happens all the time, although I only really noticed it last night when doing some tinkering.

It sounds like a there are rats running around under the motherboard. I'm not kidding either.

Its one of those sounds that you have to be there to experience properly because its just plan weird. At first I thought that a wire might have got caught in a fan or something, so I stopped all the fans but the noise is still there. I can't idenitfy the source at all even though I placed my ear against each component in turn (HDD, optical drives, PSU, CPU). Like I said, it seems to be coming form the mobo/cpu/gpu area.

I'm completed baffled. It's a broken capacitor or something like that making this noise is it?

Pjotor · Post by **Pjotor** » Thu Oct 07, 2004 7:04 am

There may be a loose part somewhere, which resonates with the vibrations from the hard drive (if you have two or more harddrives, that's even more likely).

Try unplugging the HD(s) and then start the computer, see if it goes away. If it does, use one of the decoupling methods found in these forums and on the main SPCR site. Tell us what you find!

surfed · Post by **surfed** » Thu Oct 07, 2004 11:10 am

I also have a noise from MB wich is audible when i stop all fans and put my ear inside the case. I suspect its capacitor noise, fast charging and discharging of caps can make noise....one could say you are hearing the electrons flow....nothing to worry about.

sthayashi · Post by **sthayashi** » Thu Oct 07, 2004 11:14 am

I think it may actually be an inductor making the noise. I don't think I've ever heard a capacitor make noise, but inductors are known for it.

davidstone28 · Post by **davidstone28** » Fri Oct 08, 2004 7:21 am

Okay, I think I've narrowed down the culprit, although I'm not 100% clear on this.

The noise only seems to happen when I'm using my PC as a P2P server when the HDD is writing and seeking across all of its platters (1x160gb + 1x80gb). However, the noise that I am experiencing does not emanante from the HDD - it comes from the motherboard area and sounds like electrical noise - "scheet scheet [pause] scheet scheet [pause] with a variable faint pulsing and beeping noise mixed in (think of a gentle version of what a 56k modem sounds like when its connecting ). Doesn't seem to noticeable during normal disk use - using only P2P.

I am using 1m long SATA cables (much longer than the standard ones) and Silicon Image controller on the motherboard.

Do you think this is what's causing it? The length of the leads? Is it electrical / signal noise? Something causing the motherboard components to whine? I can't say I've ever heard of such a thing but you never know...

Any further thoughts?

sthayashi · Post by **sthayashi** » Fri Oct 08, 2004 8:14 am

When I talked with MikeC a couple weeks ago, he told me an interesting strategy for finding electrical components making noise. Chopsticks. Pressing one against a components, you can feel or hear the noise it makes (if you press it against your ear).

To see if it's an inductor making the noise, look for those doughnut shaped bits with wire wrapped around them.