On 5/13/2023 7:49 AM, 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 ?
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. Is there a way (like some appropriate hardware) to make the fans work without powering up the computer ? The PSU is hermetically sealed within the PSU enclosure but the processor fan is separate and there should be a way to connect it to something to make it rotate.
1) When a bearing is worn, at low speed the fan can wobble and make a noise.
Speeding up the fan, may help it run true, for a bit. Some fans are spring-loaded,
and a spring helps "pre-load" the rotor, so it runs true for longer.
2) There are fan controls in the BIOS. You can set a fan for "No Control"
and it runs at 100% speed. On a 1200 RPM fan, this is an acceptable choice.
Some Dell computers however, they use high capacity fans, and when run
at 100%, they sound like a vacuum cleaner motor. 35CFM fans run flat-out
are OK, while 110CFM fans run that way, are too loud.
3) Vcore regulation can make "coil noise". On my current machine, I was hearing
a noise that sounded like a hard drive seek. However, when the hard drive was
replaced with an SSD, the noise was still present, and that's how I knew
I was hearing coil noise from VCore.
Fans can be run from 12VDC. You only need two electrical connections, to make
a fan that spins at 100% speed. I sometimes test 12V fans with a 9V battery (the fan might be rated at 110 ma or so, a 1 ampere fan might be too much
for a small 9V battery).
In this example, the picture of the cable is wrong, the table of values is correct.
Red should be the middle wire, and is +12V. Always check the hub label, for any hints about what you're dealing with.
https://europe1.discourse-cdn.com/arduino/original/4X/6/1/2/612cffb8df33a95d9ef9dc9200779ec41e266c38.jpeg
In this example, the bottom-right picture is correct. Sometimes, the motherboard
manual has a diagram too, as a double-check. The "tab" on the fan connector,
is what provides keying, so the correct pins touch.
https://www.dell.com/community/image/serverpage/image-id/58153iDEAF116614EE11FA/image-size/large?v=v2&px=999
Good fans have a service life of 50,000 hours.
They have different kinds of bearings -- sleeve bearings are the worst. Examples:
sleeve
ball bearing
SSO
FDB
ceramic
Fans can become noisy with little provocation. Take a quality
fan, give it a sharp shock (one good knock) on a table,
then reinstall, and you can be greeted with bearing noise.
Some fans actually get damaged in shipping. This is why, if
you buy two identical fans, and one fan makes more noise than the other,
it could be that one of the fans has received a shock that damaged
the bearing.
Fans do need to be replaced, at some point. On a much older computer,
the fans were all ball-bearing, and all of the fans in that PC needed
to be replaced, before the computer was "worn out". That's an extreme
example. Sometimes, only one fan needs replacement and the others are
fine. If the fans are the square ones, with the mounting holes, you
can buy a replacement and fit it yourself. Other frame-less fans,
it's harder to find a replacement article.
Paul
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