Re: Strange noises from the computer

On 2023-05-13 13:49, Spiros Bousbouras wrote:
> I have a computer with 2 fans , one for the processor and one for the PSU.
> Occasionally I get noises and there are 2 kinds : one is a squeaky noise and
> the other a grinding noise. The squeaky noise sometimes appears every now and
> again and eventually becomes continuous. The grinding noise appears out of
> the blue and is continuous right from the start. The 2 kinds of noises never
> happen at the same time.
> 
> The interesting thing is that when either noise happens and I start some
> demanding computation running (one which occupies around 100% of CPU time of
> one of the two cores) then after about 20-30 minutes , whichever noise was
> happening stops and does not return for as long as the computation is
> running. I can only hear a very soft whirring sound then. When the
> computation stops , the noises may not appear for some hours or days but
> eventually return. Normally the computer does not run anything demanding and
> the cores work close to 0%.
> 
> What I mentioned is the only patterns I have been able to notice related to
> the noises.
> 
> There are several questions :
> 
> 1) What causes the noises ? I can't think of any other source apart from the
> fan(s) but which is the mechanism which causes these symptoms ? In particular
> that the noises go away when one or both cores work hard but otherwise
> disappear. Putting the cores to extra work , I assume makes both fans run
> faster but which mechanical reason would cause slower rotation to produce
> noises which go away with faster rotation ?

For example, the whine going ultrasonic.

Yes, some fans can make more noise when going slow than going fast. I 
notice that on certain car. The assumption is rust in the axle or a bit 
of wear.


> 
> 2) Is there a way (BIOS or something) to make the fans run faster without
> giving extra computation to the cores ?
> 
> 3) Is there a way to find out which fan causes the noise ? It could be that
> one fan does one kind of noise and the other fan the other kind of noise. I
> opened the case once when I could hear the grinding noise but I couldn't tell
> which of the 2 fans was the cause.

Stop each one in turn with your finger. Or a painting brush, if you 
don't want to risk your finger.

When you find it, the cure would be to oil the axle, or replacing the fan.


-- 
Cheers,
        Carlos E.R.