# High pitched hissing

## DiskDoc

Hi!

I'm posting about some hardware problems that hardly are Gentoos' fault, but I'd like to ask you about it..this is a great community of knowledge  :Smile: 

It was about a week ago that I first started hearing irregular high pitched hissing noises from my now two years old homebuilt computer. Eventually, they've gotten on my nerves and ears enough for me to actually try to locate the source of the noises.

A friend suggested the power supply but I ruled it out by testing it on another computer. Next was the fans on the processor and the (according to different sources on the web, unnecessary) fan on the VIA KT266A Northbridge. I ruled them out too by slowing them briefly with my finger and not noticing any change in the pitch.

I removed all cards exept the graphics card and re-inserted the memory stick. Still same problem.

I've noticed that the noise coincides with screen activity so from the start I suspected something related to I/O actvity..a loose condenser that needed re-soldering perhaps? Shutting the screen off didn't stop the hissing.

However, this evening the machine has been remarkably quiet, only hissing now and then. After a while it struck me why - Zetagrid wasn't running in the background. And sure enough, making the CPU work made the sound come back in full force.

One guy on the web claims processors can emit theese noises. He suggested re-inserting the processor, or if that fails, buying a larger heatsink.

Well..I'll try re-inserting the processor but I really would be interested in anyone having similar experiences with their systems.

My, for this case relevant, hardware is: EPOX KHA8+ mainboard, AMD Duron 1GHz (64k cache), Abit Siluro T400 64MB (NVidia GeForce2), 256MB PC2100 DDR-RAM.

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## dberkholz

This is fairly off the wall, but perhaps it's water vapor (or water condensing near your CPU) that boils off when it hits your CPU/bottom of the heatsink. It would be louder when your CPU was working harder because it would be hotter and therefore boil more/faster.

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## Xiderpunk

The problem is most likely to be the cpufan if that is the case, some APM based motherboards regulate the speed of the fan according to the CPU load. 

Another off-the-wall possibility.. could it be EM interferrence with an on-board sound card?

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## DiskDoc

Thanks for your suggestions. I tried re-insering the processor but that didn't help. I did however notice some of the Arctic silver II thermal compund having spilled on a couple of the small resistors. I tried to clean it off but without proper cleaning fluids it's really not possible. Anyway..the compound isn't supposed to lead electricity..

I also switched off the onboard sound and chose the option "Spread spectrum" somewhere in the BIOS. I recall that having something to do with EM interference. Well, those things still didn't work.

As for the fans, I don't think it's that easy. It the hissing sounds way more electrical than mecanical. I did try slowing the fans before but I've never noticed the computer would do it automatically. I think they just keep on going at the same speed.

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## endoalpha

I will confirm that processors can make hissing, or high pitched cracking noises. I remember putting in a math co-processor in a 386 machine, and when the co-processor was utilized, it made a noise. There were no fans or heatsinks on processors back then, and I could hear the hissing faintly, even when the case was closed.

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## checkyoulater

I know your system is not a laptop. but I hear a possibly similar noise from my laptop during screen activity as well.  It seems to happen when the screen draws a lot of scrolling text, like doing a dmesg or something similar.   I haven't really though much about it, as the noise is only noticible when I make an effort to hear it.  My theory is that the built-in speakers are picking up interference from the video chipset.  

Something else you might check is your monitor.  My el-cheapo IBM E-74 monitor makes a noticible buzzing noise whenever it is powered on.  The monitor itself isn't defective, as I have heard over 25 of this exact model do the same thing.  Perhaps yours does the same, and you never noticed it until now?  Try turning off your monitor and speakers and then listen for the noise.

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## DiskDoc

I know monitors can often produce theese kind of sounds before they give up  but it's not the monitor or the speakers this time, I tried turning both off. Also, I can hear the irregular, apparently processor related hissing louder and clearer when I open the case and shove my head in.

Everyone else coming in my room also hear and are bothered by the noise so it's a little above the "barely noticeable" level.

I plan to try my processor in a friends' machine (if he'll let me) and try his processor in mine to further narrow down the source of the problem. My bet still is on the motherboard..

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## gholam

Although the water boil/hissing thing sounds somewhat rational, you gotta remember that water boils at 100C (212F). And I know he's got a Duron chip, but don't they toast at around 90C (not hot enough for water to boil)?

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## DiskDoc

According to the thermal sensor for the (under the?) processor my Duron doesn't get any hotter than 52 degrees Celcius..

Hmm..the bastard's been hissing a little more than usual today. I keeps at it almost constantly although the CPU seems to be idling..

Another thing I forgot to mention: Before the system started booting Linux i pressed the power button to suspend the system (set to STR in BIOS) and the hissing stopped. Well, as I understand it, everything pretty much stops except for current to the memery chips so it's not really that surprising.

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## DiskDoc

I discovered something interesting tonight. Pulling out the AGP graphics card and using a PCI graphics card instead removed the hissing noise completely! I have yet to try the AGP card in another computer to find out if it's the source of the problem or if it has something to do with, perhaps, the AGP bus.

I'm not sure what the custom is in the forums... Please tell me if I should edit and add to my previous posts instead of replying to my self and hence bumping it.

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## checkyoulater

Hmmm.  I wonder if the noise could possibly be some screwy capacitors on the AGP card?   My GeForce 4 has a lot of caps on it, and while I haven't heard of defective caps on a video card, I have certainly seen them on crappy motherboards.  I don't remember the layout of a Gf2.  

Look on your motherboard for some capacitors with perhaps some fluid leaking out the tops of them.  This used to be a big problem with an old Soyo board I used to have.  It never happened to me, so I don't know it that could even cause your symptoms.   But hey, it's worth a shot...

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## DiskDoc

Seems you were right about the capacitors. I found one right in the middle of the motherboard, leaking from the top. I'll be whining/giving feedback to EpOX about it but since my 12 month warranty has run out I suppose I'll have to try and replace it myself.

But it's only the 19 month since I bought the board. I think you should be able to expect longer lifetime on PC hardware..six years at the least   :Mad: 

Before I saw the capacitor I also tried another AGP card to no avail.. and noticed it did hiss with a PCI graphics card after all.

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## Ziraku

If you're feeling really crazy, you could always detach that capacitor and resolder a new one of the same capacitance...Seemed to work for me when my power suppy's capacitor exploded.

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## DiskDoc

That's what I'll try to do.. I can't afford a new motherboard right now. Cool that you got away with fixing the power supply! I wouldn't dare go poing around there myself.

The damnest thing just happened..that's what I really came to write about.

I bought the game Master of Orion III second hand and met the guy who was selliing it. We got to talk about this and that and I mentioned my "hunt for the high pitched noise". Immidiately he asked me "is it an EPoX motherboard"?

I was astonished. How could this man possibly know that?! Turns out he worked as a computer service technichan for a while. He said a few of the EPoX models suffer from failing capacitors and a lot of them had come in for repairs. The 8KHA and 8KHA+ and one or two others.

So here I've been roaming the web for answers and pulling my computer apart (and my hair) for a week when I suddenly stumble over a guy in the same city who knows all about it. Funny..

Anyway. I think this thread should be valuable to others with the same problem. Hopefully the forums are catalogued by Google so someone else finds their way here.

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## elzbal

 *DiskDoc wrote:*   

> urns out he worked as a computer service technichan for a while. He said a few of the EPoX models suffer from failing capacitors and a lot of them had come in for repairs. The 8KHA and 8KHA+ and one or two others.

 

I'm glad your problem was resolved! The bad-capacitor thing hit a lot of motherboard manufacturers, but some more than others. Maybe you can ask this guy for a good source for replacement capacitors? I recommend you buy more than one - capacitors tend to be somewhat inexpensive, and it might be nice to have more than one in case another goes bad.

Cheers!

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## DiskDoc

Well, finally, it turned out the leaking capacitor on my motherboard wasn't the problem after all. Hopefully this post is the last one, bringing a true end to the story.

A friend helped me replace the previously suspected capacitor on the MB but when I got home and powered everything up - the noise still remained. Suffering for a week or two I still believed the problem was somewhere on the motherboard.

One day I experimented with another computer putting its older SIS-chipset motherboard with K6-II processor in my case instead of my own. The hissing noise became different then, completely gone at least at startup. I realised the power supply was broken after all! The noise eminating from some failing component inside the power supply seemed dependant on the power load. That was why I didn't hear the noise before when I tested the power supply on an older, less demaning computer.

A week later since my happy discovery I now have a nice new power supply with an extra 50 Watts and temperature-controlled low-noise fan  :Smile:  I was going to fix the old power supply myself but didn't actually get to soldering..being afraid of current still hiding in the silent silos of the capacitors.

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## davidn

thanks for that DiskDoc - I think I have a pretty similar setup to yours and I've been having that hissing too. I especially noticed it when I was dragging windows around the screen... but I thought I could hear it under the sound of the hard drives too.

One day when I was getting particularly confused/annoyed with it I tried hunting down the exact source with a crappy little mic and some head phones.. but I just couldn't work out where it was coming from... and it's been bugging me for months...

thanks!

(and now I've got a good excuse to upgrade my power supply!)

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