[geeks] You forget how quiet the Mac Pro is until...

[Arno Kletzander]

"Aaron Finley" <aaronfinley at gmail.com> wrote:
> Sun v20z.  No less than 6 high-rpm fans, as they move into and out of
> phase with each other you get a high-pitched ringing in addition to
> all the noise.

Gah, that's similar to an effect I remember all-too-well from the 3Com Superstack II Switch (3C16980) that I had sitting *on my desk* for several weeks some years ago. We in the office called it the "Jericho trumpet".

Even in normal operation that beast was loud enough for an office environment, but sometimes it would get worse...the rpm of the two fans in there would start to oscillate, I suppose because the fans "loaded" each other by means of backpressure buildup inside the enclosure - the result was a pulsation of the noise both in pitch and intensity. Often you could end that "surging" with a good whack to the area where the fans were.

Ah, the memories...
-- 
Arno Kletzander

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