Problem with noisy fan

[blueroomelectronics]

Then why did you post a photo of a power supply in an earlier post?

 

[whiz115]

Then why did you post a photo of a power supply in an earlier post?

because PhillDubya asked for it.

What brand of computer psu are you using? Just out of curiosity....

 

[blueroomelectronics]

Ok then buy a fanless CPU cooler or one that's designed to be quiet. You can also get noise dampers for your case.

 

[Techie7]

FAN PROBLEM...!
a fan prblm or pwm connection prblm..replace thats all..it'll work.

 

[whiz115]

FAN PROBLEM...!
a fan prblm or pwm connection prblm..replace thats all..it'll work.

Techie7 are you sure??
happens alot??? do you think i should try the mod with the resistor and the capacitor?

but why the problem became obvious after i changed the motherboard?

 

[Techie7]

yes..!
just buy a new fan for your nwe motherboard. Old fan is 4 your old mb and u need new fan for new mb. Else who is going to make fan circuit for new mb.

 

[whiz115]

Old fan is 4 your old mb and u need new fan for new mb. Else who is going to make fan circuit for new mb.

the fan didn't came with the motherboard, the fan is aftermarket...

ok...i'll see what i'm going to do with it.

thanx guys.......

 

[PhillDubya]

yes..!
just buy a new fan for your nwe motherboard. Old fan is 4 your old mb and u need new fan for new mb. Else who is going to make fan circuit for new mb.

What?

A fan is a fan. They will work with a motherboard regardless, they are designed to; especially aftermarket fans. A PWM, is a PWM, to a CPU fan, regardless of the motherboard, motherboards don't have specifically designed PWM signals for their own proprietary fans.

@Whiz:
That being said, the fan could be faulty, but it is most likely a problem with the motherboard. You stated everything was fine, until you changed the m.board.

IF it is a PWM problem, the PWM is generated by the motherboard, and once again reverts back to a motherboard problem.

Like you stated, try to RMA it.

 

[MrAl]

i don't need headphones to hear the noise!!!!

and also it's not a solution to disable the PWM control wire so i can
totaly stop the electrical noise.

[edit]

@MrAl do you think it will work? not all motherboard have the same fan control IC.
the PDF link i gave is a random one i got while i was searching the net.

Hi Whiz,


I am going on the assumption that the new motherboard has
a better switching transistor or just faster rise and fall time
or something like that, which would create more noise.

If there really is something wrong with the motherboard that's
a different story, but then i doubt it would be able to control
the fan speed at all.

Any possibility you can post a pic of your fan and maybe
the motherboard too?

The fan has three pins, four pins, or just two pins?

BTW, with a resistor of 1k the caps to try would start at
0.01uf, then 0.1uf, then 1uf, then 10uf.

 

[whiz115]

problem FIXED!
no need for a resistor! just one 1uF capacitor from PWM control pin to GND pin! when i said that i tried few capacitors but they did nothing... i was connecting them from +12V to GND because i couldn't imagineeeeeeeeeeeeeeee!!!!!!!!!!!!!!!!!!!!!

something i've noticed and i don't know if it is ok or not... is that when i'm using the 1uF capacitor and i have the BIOS function at "ultra Silent" the RPMs of the fan are getting lower than without the capacitor.

so now... i know two things!!! first the PWM is full of ripple noise because of the reason MrAl gave (?) and second that the motherboard probably has missing components or that is kinda faulty (?)

if it is faulty i think i should RMA it...but how am i going to explain that to the dealer store?

 

[Nigel Goodwin]

It's probably your fan that isn't suitable for PWM control - not a fault on the motherboard. PWM is supposed to have 'ripple', in fact it's 100% ripple - that's why it's efficient.

 

[Techie7]

whizzz....
1microfared cap from pwm to gnd?
sometimes you lost the noise because the rpm of fan is slower now. is that a proper way or will it affect the mb? sometimes your fan speed may controlled by pwm from mb or new mb made your fan run faster than older one. y not safely try anoother fan?

 

[whiz115]

It's probably your fan that isn't suitable for PWM control - not a fault on the motherboard. PWM is supposed to have 'ripple', in fact it's 100% ripple - that's why it's efficient.

hi Nigel

when i'm saying ripple i mean that it's not totaly square wave as it should
but it has ripple noise on it....perhaps i'm not explain it well?

whizzz....
1microfared cap from pwm to gnd?
sometimes you lost the noise because the rpm of fan is slower now. is that a proper way or will it affect the mb? sometimes your fan speed may controlled by pwm from mb or new mb made your fan run faster than older one. y not safely try anoother fan?

ok...i'll try it with the capacitor and the fans at full speed and i'll update.

well i don't know if it can harm anything... the only thing i've noticed is that the fan speed lowers more with the capacitor than without it if you have selected the"Ultra Silent" mode from the bios... as far as i can understand the capacitor only shapes the PWM Bill said that the link i gave shows an integrator.

 

[wireaudio]

Totally unrelated to the question... but related to the noise:

Funny, my video card makes funny noises (i got a GTX 280) whenever im on the world of warcraft character select screen... Not like its even intense for this video card lol.

 

[whiz115]

Totally unrelated to the question... but related to the noise:

Funny, my video card makes funny noises (i got a GTX 280) whenever im on the world of warcraft character select screen... Not like its even intense for this video card lol.

@wireaudio ferrite vibrations or maybe the problem you read here.


update...

Now my fan works at 2540RPM (full speed) and there are no weird noises.
Nigel if you don't agree with what i did then say it!

 

[MrAl]

problem FIXED!
no need for a resistor! just one 1uF capacitor from PWM control pin to GND pin! when i said that i tried few capacitors but they did nothing... i was connecting them from +12V to GND because i couldn't imagineeeeeeeeeeeeeeee!!!!!!!!!!!!!!!!!!!!!

something i've noticed and i don't know if it is ok or not... is that when i'm using the 1uF capacitor and i have the BIOS function at "ultra Silent" the RPMs of the fan are getting lower than without the capacitor.

so now... i know two things!!! first the PWM is full of ripple noise because of the reason MrAl gave (?) and second that the motherboard probably has missing components or that is kinda faulty (?)

if it is faulty i think i should RMA it...but how am i going to explain that to the dealer store?

Hi again Whiz,

That's great to hear, but the solution isnt that great to hear.
The reason i say this is because there was no series resistor included
in the 'fix'. The series resistor was supposed to be there for at least
two reasons:
1. To help the cap work better in filtering
2. To protect the Mother Boards drive circuit from high peak currents

Now we can do without #1 above, but without #2 we risk doing
long term damage to the MB, which would be hard if not impossible to
fix later on.
Solution? Simply add a series resistor. Even 100 ohms is better than
nothing, and this could allow a smaller cap value too.

I'd start with 1k and then cap values:
0.01uf, 0.1uf, and 1uf (now that we know 1uf works without R).
If that doesnt work, then 200 ohms and those same cap values,
starting with the lowest value and working toward the highest.
If that doesnt work, 100 ohms and same cap values, etc.

I'd hate to see something happen to the MB so the fan doesnt
work at all anymore, or worse.

The idea is to use the highest value resistor that will work and the
lowest value cap what will work. This is best for both the fan and
the MB alike.

Good luck with it...

 

[whiz115]

MrAl really thank you that you're showing interest for my stupid little problem!

As you initialy proposed i tried it with a 1k resistor and 1uF capacitor... there was no noise but when i was changing the fan speed mode from the BIOS, the fan didn't responded... so i was lowering the resistor value until 220ohm where the fan started to respond and i was able to choose between two modes "performance" and "ultra Silent" but there were no response for the rest of the modes. Then i lowered the resistor to 47ohm where it looks like the system behaves best and it worked all day fine!

because i wanted everything to look nice and tidy, i did a pcb with the good old windows paintbrush...i wanted it to be as small as a mobile phone SIM card, and accidentaly became so small that that even the connectors can't fit so well