Re: Why so much HD activity?

"J. Clarke" <jclarke.usenet@xxxxxxxxxxxxxxxx> wrote:

>Terry Pinnell wrote:
>
>> Terry Pinnell <terrypinDELETE@xxxxxxxxxxxxxxxxxxx> wrote:
>>
>>>"J. Clarke" <jclarke.usenet@xxxxxxxxxxxxxxxx> wrote:
>>>
>>>>Terry Pinnell wrote:
>>>>
>>>>> "Rod Speed" <rod_speed@xxxxxxxxx> wrote:
>>>>>
>>>>>>steve@xxxxxxxxxxxxxxxxxxxx wrote
>>>>>>> Terry Pinnell <terrypinDELETE@xxxxxxxxxxxxxxxxxxx> wrote
>>>>>>
>>>>>>>> When just spinning, it's fine. But most of the time
>>>>>>>> there's 'activity', and that makes a sort of deep
>>>>>>>> 'throbbing' sound which gets rather wearing.
>>>>>>
>>>>>>> It could be a beat frequency between
>>>>>>> the drive and a fan or another drive.
>>>>>>
>>>>>>Nope, you'd see that when just spinning.
>>>>>>
>>>>> No, Steve is right, I was mistaken/misleading in my initial
>>>>> description. Now that I've been more careful and also taken the cover
>>>>> off, I can clearly see/hear that the 'throbbing' is coming from the
>>>>> fan mounted on top of the Athlon CPU heat sink.
>>>>>
>>>>> It's intermittent and it's not consistently the same sound. I can
>>>>> alter it by touching the case.
>>>>
>>>>If you can alter it by touching the case it's either something loose or a
>>>>panel resonance. If it's something loose find out what and tighten it.
>>>>If it's a panel resonance there are at least three fixes--different case
>>>>with different resonant frequency, alter the RPM of the fan so it's no
>>>>longer in resonance with the case, or add some mass and damping to the
>>>>resonant panel, which you can do by sticking in some purpose-made
>>>>soundproofing (Dynamat Extreme <http://www.dynamat.com/> is the gold
>>>>standard--"ice and water shield" that you can get in the roofing section
>>>>building supply stores is cheap and works well but read all the fine
>>>>print, if you go to <http://www.silentpcreview.com> you'll find
>>>>discussion of other materials that work well).
>>
>> An immediate finding is that one of the 4 screws is not 'threading',
>> IOW is completely loose and cannot be tightened up. However, all the
>> others are firm (and I've just given them another 1/4 turn). The
>> 'resonance' diagnosis is one possibility, which maybe I could cure
>> with a replacement fan, or adding a couple of diodes in series with
>> leads to reduce voltage applied? But how about bearing failure or dust
>> build-up? As you saw from my photo, there's a fair amount of dust
>> inside the fan. Could this unbalance it, and - combined with wear on
>> the presumably cheap bearing - cause this throbbing? It changes every
>> few minutes, sometimes deeper sometimes higher.
>
>Blowing the dust out won't hurt, but an unbalanced fan wouldn't explain why
>the sound goes away when you touch the case (I presume you mean by "case"
>the metal box that forms the outer shell of the computer). As for the
>bearing, if the fan is coming up to full RPM the bearing is not likely to
>be causing a balance problem--if it's a sleeve bearing and it's failing it
>would be slowing the fan down, if it's a ball it can make noise for a long
>time before it stops functioning as a bearing. I wouldn't try oiling it
>unless I was sure that it was the problem--with the machine shut down does
>the fan spin freely with no feeling of roughness when you turn it by hand?
>If so then the bearing is functional.
>
>If it's sometimes louder and sometimes softer then there could also be a
>beat-frequency component resulting from two devices at nearly the same RPM
>going in and out of phase with each other.

Thanks, John. As you've probably now seen from my subsequent post, all
now OK. BTW, by 'case', I was referring to the fan case.

--
Terry, West Sussex, UK
.

Relevant Pages

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