"Oscillating" fan noise

[asintu]

I think one of my fans (didn't yet identify which one) produces somewhat of an "oscillatory" noise....like normal, little higher pitch, normal, little higher pitch etc.
Something like this...veee-ahhhhh-veeee-ahhhhh etc. ("veee" is higher pitch )
Is this a normal thing or what's the problem here?

 

[Zepper]

No, in general, that is not normal. Tell us more about this fan. What make and model is the fan and how old, what case is it in, front or rear or other, what power is the fan connected to (mobo, fan controller, straight to PSU) etc.?

.bh.

 

[asintu]

Originally posted by: Zepper
No, in general, that is not normal. Tell us more about this fan. What make and model is the fan and how old, what case is it in, front or rear or other, what power is the fan connected to (mobo, fan controller, straight to PSU) etc.?

.bh.

i've listened to all fans and from what i can tell the one responsible for this is the fan on the e8400

 

[Zepper]

Connected to the mobo connector then it may be controlled and cycled up and down as needed. About the only way around that is to turn the cpu fan speed control off in the BIOS or connect the CPU fan to a separate controller and set it to a fixed speed high enough to keep the CPU safe and low enough to keep the noise tolerable. May be possible to get a better fan for the CPU cooler.

.bh.

 

[asintu]

Originally posted by: Zepper
Connected to the mobo connector then it may be controlled and cycled up and down as needed.

.bh.

Ya but shouldn't it go up and down depending on temperature? The noise cycle i'm hearing is the same all the time.

 

[Fullmetal Chocobo]

Originally posted by: asintu

Originally posted by: Zepper
Connected to the mobo connector then it may be controlled and cycled up and down as needed.

.bh.

Ya but shouldn't it go up and down depending on temperature? The noise cycle i'm hearing is the same all the time.

I might be absolutely wrong in this, but I recall Galvanized Yankee mentioning something about this once. It had something to do with multiple fans together in a system and them resonating. Once again, I could be wrong... It was such a long time ago that I haven't been remotely successful in finding the thread though.

 

[asintu]

Originally posted by: Fullmetal Chocobo

Originally posted by: asintu

Originally posted by: Zepper
Connected to the mobo connector then it may be controlled and cycled up and down as needed.

.bh.

Ya but shouldn't it go up and down depending on temperature? The noise cycle i'm hearing is the same all the time.

I might be absolutely wrong in this, but I recall Galvanized Yankee mentioning something about this once. It had something to do with multiple fans together in a system and them resonating. Once again, I could be wrong... It was such a long time ago that I haven't been remotely successful in finding the thread though.

hmmm..interesting idea, might be it. gotta first set a fixed speed for the cpu fan see what it does.

 

[Bluefront]

I think Fullmetal Chocobo has it covered. This sort of fan noise happens when two fans create the noise when running at the same time. Turning off one or the other should stop the sound. If that cures the problem......it might be time for a fan swap, or a fan rpm change. A different fan even at the same rpm might fix the problem. This can be tricky to solve.

 

[Fullmetal Chocobo]

Originally posted by: Bluefront
I think Fullmetal Chocobo has it covered. This sort of fan noise happens when two fans create the noise when running at the same time. Turning off one or the other should stop the sound. If that cures the problem......it might be time for a fan swap, or a fan rpm change. A different fan even at the same rpm might fix the problem. This can be tricky to solve.

I take no credit, except for remembering what Galvanized Yankee said. And I do remember him saying that a quick remedy was to decrease the speed of any single fan (for those involved in the resonating effect), and it would take the noise away. So if you have them on a fan controller, just decrease or increase the speed of one.

 

[asintu]

problem is I dont know which 2 are resonating since I have 4 in total..most probably its the cpu and case fans if this is the case..i'll try playing with the speeds.

 

[asintu]

installed SpeedFan and tried to change the cpu fan speed but it's stuck at around 1300rpm no matter what i try. could a bios setting be involved or something?

 

[Rubycon]

A finger on the hub will change the speed guaranteed and is the quickest way to identify possible near speed offbeat sounds. A really good fan controller should have a synchronizing clock (like wordclock used in pro audio) to make sure the fans are spinning at the same speed however it would need to work at the commutatorless driver level which would not be very practical for typical pc use. (but nice nonetheless!)

 

[asintu]

maaan this thing is driving me nuts...especially at night when all i hear is the computer....wanted to disconnect the fan from the mobo but i can't pull it out!!! it's stuck my some mechanism. i really wanna make it stay at a constant speed!!! need suggestions.

 

[Gillbot]

The shift in pitch you are hearing is called Modulation.

 

[asintu]

Originally posted by: Gillbot
The shift in pitch you are hearing is called Modulation.

is modulation ok for cpu fan speed?

 

[Gillbot]

If you have speed control enabled, yes it can be normal. Otherwise it should not modulate. Try plugging the fan into a different header, if it continues, try a different fan.

 

[PianoMan]

You first need to determine if it's a single fan doing it or multiple fan resonance (modulation).

Disable all your case fans temporarily, and select "full fan speed" in your BIOS. Turn on your computer and listen.

Individually start each case fan and check if any one of them do it.

Then start with just the CPU fan again, this time on auto speed control, and gradually turn on each case fan until all of them are running. You should be able to detect fan noise interaction at this point.

Don't forget you've got a fan in your PSU.

After going thru this drill and jump starting my PSU alone to check that fan, it turned out the modulation noise I had experienced recently turned out to be a noisy hard drive.

 

[asintu]

Originally posted by: PianoMan
You first need to determine if it's a single fan doing it or multiple fan resonance (modulation).

Disable all your case fans temporarily, and select "full fan speed" in your BIOS. Turn on your computer and listen.

Individually start each case fan and check if any one of them do it.

Then start with just the CPU fan again, this time on auto speed control, and gradually turn on each case fan until all of them are running. You should be able to detect fan noise interaction at this point.

Don't forget you've got a fan in your PSU.

After going thru this drill and jump starting my PSU alone to check that fan, it turned out the modulation noise I had experienced recently turned out to be a noisy hard drive.

i've listened closely and its my hdd..time to return it

 

[PianoMan]

Interesting you had the same issue. I was going nuts trying to pin down which one of the fans was doing it and in the end it was the HDD.

Not sure if mine is about to fail, but there isn't anything really valuable on it.

 

[asintu]

are the 4 white pins from the bottom of the cpu cooler (the ones that you can see only on the back of the mobo) supposed to be white all over the black pin they are surrounding? Or are they supposed to have the white part opened up a little leaving space to see the black pin? If it's supposed to be white all way round then mine are broken.

 

[VirtualLarry]

The white pins are in two parts, where the black pin gets slid in between the white parts to lock in into the mobo. I think your ok.