Unkown source is causing specific fans to buzz/tick

[Placid]

Almost year ago, I embarked on a project to replace a 92mm 2850 RPM fan in the PSU. 2 threads, 3 fans, and $34 wasted has lead to a new project: to find the source that is causing the buzzing/ticking of all new 92mm fans, before I seek another replacement.

Link to my previous thread. It was becoming apparent that the buzzing was probably not from the fans themselves. Due to the twist in the topic, and suggestions for fans are still flowing in, I am continuing that discussion here.

Panaflo and both Delta 92mm 2450 RPM fans (all with RPM sensors) buzz. I tested them on a totally different computer and all buzzed there as well. This is what ThermalFX said about the Deltas via e-mail:

I have tested the fan you returned along with 6 others of the same model from the same factory box lot.
Neither I nor any of the other people working here could hear any audible sounds coming from any of the fans other than the typical blade noise.
We could not hear any clicking, popping buzzing or any other noises such as you described to me.
We placed all the fans on a scope and found them all to exhibit the same wave patterns during testing voltages of 7 through 13 volts.
There were no noises or vibrations during the tests.
To eliminate any further doubt, I have packaged and shipped you another fan as a replacement, different from the one which you returned.

What is known:
-Buzzing is isolated to 92mm 2450 RPM fans so far, was not present in the original 92mm 2850.
-Buzzing gets worse the lower the voltage, but disappears at full speed.
-Where they are connect to makes no difference.
-Does not affect 5 other fans of different manufacturers/RPM/sizes in the computer.
-PWM is not a factor. There is none.
-Sample variance is ruled out. Cause for the buzzing is determined to be from another source.
-Possible suspect: PSU, but that would mean the current computer and the one used to double check the fans would both have the same exact flaw.

What could be causing the buzzing of those fans specifically?

[confusion]

Are the two PSUs the same model, or the same brand? If so then there's at least a possibility there's something about their output that makes the buzzing. If not then that would seem very coincidental.

[Aris]

bad power, Get a UPS to clean it up.

likely some stray frequency in the power lines that has a random effect of a certain rpm of a fan. probably has something to do with how those specific fans are wound electronically. just one of life's random coincidences.

[Placid]

Are the two PSUs the same model, or the same brand? If so then there's at least a possibility there's something about their output that makes the buzzing. If not then that would seem very coincidental.

Totally different PSUs. Different model, different wattage, different orientation, etc.

bad power, Get a UPS to clean it up.

likely some stray frequency in the power lines that has a random effect of a certain rpm of a fan. probably has something to do with how those specific fans are wound electronically. just one of life's random coincidences.

Bingo! Aris, I think you hit the nail right on the head. This seems to be the most logical explanation. I live in a pretty old building, circa 1939. Much of the electrical wiring may have never undergone any upgrade, or if it did, it would have been many decades ago.

Most of the accessible outlets are at least two generations old. They're neither polarized, nor grounded. The only way I could make use of them is to use adapters in between. I know it's not a good idea, but it's a choice between adapting it to use a computer and most electronics, or be in the dark ages. I asked the landlord about it, but they think it's too much trouble to rewire.

A UPS is going to cost some pretty pennies. Or maybe try a different RPM. Why, oh why, does everything cost more money in the end... hopefully, there won't be any more hidden obstacles. Even moderate silencing can cost quite a bundle.

[xan_user]

UPS' imo are part of the total cost of ownership with computers. and electronics for that matter.

You may run into ground fault problems in a house that old...

There's some threads here about finding quiet ups', search a little and save some headache before you buy one thats fan is on all the time.(like I did-oh but it was a deal...)

[Placid]

I'm still reluctant to buy a UPS. There's no guarantee that it will solve the buzzing, and possibly wasting a big chunk of money in the process.

In another attempt at the issue, I discovered that temporarily unplugging a number of electronics from the surge protector (that the computer is connected to) reduced the buzzing a bit. It's a marginal improvement, but I'll have to plug them back in since they're needed, like the TV and the florescent light (probably the biggest offender as florescents often produce interference). There's no other power source to relocate them to unfortunately.

[xan_user]

Not having a UPS is like keeping your computer under a leaky sink, sure it works now but some day...

If what you say is true about the power strip is true id defiantly say its the dirty voltage.

Buy a 'decent' UPS and try it. If it doesn't solve your problem you can always take it back.

[proc]

Hi,

most of the UPSs I've seen require proper grounding, so check before buying one.
I think an EMI filter or two could be enough for your needs.

BTW if you manage to obtain proper grounding from the landlord do yourself a favour and buy a UPS

[Placid]

If the UPS does not help, then I would simply get killed on shipping alone. Moving big heavy bricks around aren't cheap. Alas, I've lost a lot of money on previous attempts that lead to the Panaflo fan issue. Adding them up would total to nearly $75, mostly due to shipping. I'm very weary on any more risky spending.

proc is right about proper grounding. There isn't any, so a UPS might encounter problems of its own.

My surge protector, APC Pro 8T2, provides EMI and a slew of other filtering, although it does not seem to work, probably due to the the absent grounding.

No go on the landlord. They're not going to do it.

[xan_user]

My folks have a faulty ground in their house but still benefited from a ups.

Where are you located placid? I have an extra one lying around, and am willing to pay up to $20 to ship it as a gift.
If it doesn't work for you, all i ask is to just "pay it forward" and give it to someone else.

[Placid]

That's very generous, xan_user. I might take you up on that offer, but if I do, I'm paying for the shipping. There's no way someone who is helping me out should pay to do so. I'm 2000 miles away from you, in NY. What model/brand is it?

In the meantime, I'm still not certain if a UPS will truly solve that one specific buzzing issue when everything else have failed. Seems too "magical" of a solution.

You say a UPS worked for you folks with faulty grounding? How did they benefit from it? What problems did it solve?

[xan_user]

8-10 yo cyberpower 99, it was a 350va but they upgraded me to a 500va battery the first time i replaced it.
Just installed a brand new CSB 500va battery.

It wasn't there to solve any particular problem other than voltage spike control and brown/black out protection. And saving and shutting down PC in case of extended blackout. The ground fault light only came on when plugged in to a few of their outlets, not all. (ok we didn't try em all just a few.)

Just let me know.

[Placid]

I was looking into UPS', and then it dawned on me. My surge protector does the same things as a UPS minus the battery. The APC Pro 8T2 was a full fledged premium model, not a dinky box with outlets. It already provides the lightning/spike/surge/RFI/EMI/etc, and blackouts are rare.

At this point, a UPS would just be redundant and probably won't solve the isolated buzzing. Think I'll pass on the offer, xan_user.

[xan_user]