Odd noise, apparently from motherboard.

[spackle]

I just got a Dell Q6600 quad core desktop that has a kind of intermittent high pitched hissing, crackling type noise emanating from what seems to be the mobo. It kind of sounds like shh-shhhh-shh-shhhh-sh. I don't think it's a "whine" type of noise as you might get from a graphics card revving up. Rather It's a faint static-like noise, and unless you listen from the rear of the case you can barely hear it. I have very sensitive hearing, so I guess that's why I picked up on it.

Anyway, at first I thought it was a hard drive seek noise, because it kind of sounds like that... But after opening the case and listening closely, it really seems to be coming from right around the CPU. So, after a bit of digging around I found that the Vista's power settings can affect the noise. For instance, if I set the maximum processor power usage to be anything lower than 100% it does it almost constantly. In addition, I checked in Core Temp and when the CPU voltage drops down to 1.1625 is usually when the sound occurs.

The noise doesn't bother me since I can barely even hear it from the front of the case. And I REALLY hate to deal with Dell over it... But I wonder if it's a symptom of an impending failure.

Any ideas on what this could be?

[spackle]

Re: Odd noise, apparently from motherboard.

Just an update here.

I rolled up a sheet of paper, put it to my ear, and tried to pinpoint exactly where the noise is coming from.

It appears to be coming from these black box things. When the paper is the area highlighted, I can plainly hear a noise that sounds like static.

What are these things?

[Harvey]

Re: Odd noise, apparently from motherboard.

Looks like a fan to me.












Actually, I think what your hearing is the inductors. Tricky to tell from the photo, but I'm guessing that's what the black blocks are next to the Mosfet's.

Its fairly normal for them to make a high pitched squeak/white noise type of sounds. Just be aware that it could be a sign that the capacitors are starting to age (if it starts to make that noise but never had before), but they can also make that noise normally, and it often varies depending on the CPU load.

My ASUS P5N32-SLI makes just such a noise, and always has from the day I got it. Once you put the case cover on its almost inaudible, but you can occasionally here it when the CPU is being thrashed.

[spackle]

Re: Odd noise, apparently from motherboard.

Oops, sorry about the lousy photo

Yeah, this is more like a white noise as opposed to a whine. When I listen through the paper tube it almost sounds like a bowl of rice crispies, so I suppose it could be a capacitor sizzling too. But it definitely seems to be coming from the black blocks.

The odd thing is that it does it almost constantly when the CPU is throttled. Whenever the CPU revs up it stops.

[kikkoman]

Re: Odd noise, apparently from motherboard.

yup, that's an inductor that hasn't been properly potted.
i'm not sure if it's fixable - that depends on the core.
alternative: return it and have the whole board exchanged. probably the best option if it's a new system.

[willawake]

Re: Odd noise, apparently from motherboard.

might be the design though, i installed two albatron boards that did some fizzing with heavy hdd access etc. no other probs though and stable. my router does this since new also

[spackle]

Re: Odd noise, apparently from motherboard.

Well, for what its worth, I did speak to Dell about this, and according to their support rep "many users are facing this issue." However, I got the distinct feeling the guy didn't have a clue about it because I had to keep reiterating that it wasn't hard drive noise. Anyway, they're supposed to "research" it and call me back on Monday.

The system runs great other than the noise. If it's just harmless resonance from an inductor I'd happily live with it rather than having a hassle with Dell over an exchange that might do the same thing.

I don't suppose there is a way to rule out bad caps, or other signs of impending doom?

[Harvey]

Re: Odd noise, apparently from motherboard.

You say you've monitored the core voltages - how much do they vary? Does the 12V vary in sync with the VCore or is it flopping all over the place?

[kc8adu]

Re: Odd noise, apparently from motherboard.

i just had 2 optiplex 520 sff boxes in with bad power supplies.
they hissed a bit but it went away after a recap.
caps on +12 were bad.
hiss came from vrm section.
unit was quiet and stable after the repair.
vcore clean and all caps i could see were mcz.

[spackle]

Re: Odd noise, apparently from motherboard.

Well, I'm not quite sure exactly what I should be looking at, but in all the monitoring programs I've used the +12V varies between 12.03 - 11.97. VCore1 varies between 1.14 - 1.28 and VCore2 seems to stay steady at 3.06.

VCore1 varies the most. There also seems to be a slight difference between the monitoring programs.

[Fizzycapola]

Re: Odd noise, apparently from motherboard.

This looks like more than 10% Vcore voltage fluctuation. Fluctuation can be because of failing capacitors. On my motherbaord (3 phase power Athlon) after recapping fluctuation was reduced to within 2% Vcore.

Aswell as using speedfan voltage monitor, look in BIOS aswell and record minimum and maximums you see.

It's preferable that atleast in BIOS you see no more fluctuation on Vcore than 5%, prefeably under 3%, I would have thought modern quad phase and higher power systems could achieve this. If the fluctuation range increases over time then it's surely indicative of imminent failure.

Removing component noise can be tough to find which part makes the noise. I'm in the process of trying to silence noise from a Linksys router without much success, so far I have ruled out the capacitors and exposed coils and am looking at the ADSL line in side including the relay - my ear says it's the relay but I can't be sure.

[WNG]

Re: Odd noise, apparently from motherboard.

Had an ECS motherboard that squealed horribly. Eventually got rid of it. Suspected inductors on that one.
I did have an SMC router which hissed out of the box. It crapped out when subjected to a brown out. The replacement unit has no hiss. And has survived a number of power issues.
Bottom line, it's not supposed to emit sound if constructed properly.

[kc8adu]

Re: Odd noise, apparently from motherboard.

had a linksys router brought in by a friend with good hearing like mine.
he plopped it down on my bench,plugged it in, and said any questions?
it had a 10uf 250v cap on the output of the +5 vrm!
talk about an assembly line screwup!
that thing would have gotten shot if i had to use it unrepaired!