How to track down a noisy fan ??

[Fritz]

Got one going Wa Wa Wa Wa Wa Wa, etc. If I unplug any fan the rest speed up to full blast and the Wa Wa Wa can no longer be heard. This happens no matter which fan I unplug. This is about to drive me nuts. Help please.

 

[alex_stief]

You can make a cheap directional noise detector™ using a sheet of paper. Roll it up into a tube, place one end at your ear, and scan the area of interest with the other end.

 

[Rock]

I touch the hub with my finger to slow the fan and determine if the noise changes. Hub = the flat area in the center where the blades are not present. Your fingers, your choice.

 

[Fritz]

The fan wall is composed of dual fans with individual connectors i.e. 2 connectors for each fan unit. They are in a 2u chassis and are larger than 1u fans. I'll try the finger trick. I thought of this but they're spinning at 5 to 6k. Kinda don't want to lose a finger.

 

[britinpdx]

If I unplug any fan the rest speed up to full blast

Good suggestions so far, I'll offer an alternative which may be tedious ... possibly power down the server completely so the BMC has to "register" any fans before power up. (Pretty sure this works for Supermicro boards, but I have used Intel boards in the past that require a one time "configuration" to be setup where this may not work)
This way you could at least disconnect one fan at a time while powered down.

 

[Fritz]

Good suggestions so far, I'll offer an alternative which may be tedious ... possibly power down the server completely so the BMC has to "register" any fans before power up. (Pretty sure this works for Supermicro boards, but I have used Intel boards in the past that require a one time "configuration" to be setup where this may not work)
This way you could at least disconnect one fan at a time while powered down.

Thanks. I'll give that a try.

 

[edge]

Replace them all. Time is money.

Or, get your replacement fan and serially substitute it for each existing fan until the noise goes away.

 

[pricklypunter]

Use a knitting needle/ plastic rod/ straw etc pressed to your ear. Just make good mechanical contact above each fan bank, moving along above all of them. The bad one will be pretty obvious as it will be both louder and clearer when you are touching it

Depending on just how bad it is, you might actually be able to tell easily which one is the culprit simply by restricting it's air intake with a strip of card