# Noisy PSU on startup (cold amb temp)



## Music (Apr 27, 2005)

Hi, this is my 1st post here.

Neally 2 yrs ago I had a PC made up with the specs below. I inquired about my PSU fan making a horrble grating sound. Similar to an egg beater or food mixer :4-dontkno. It happens when the amb. temp is below around 10degr and happens as soon as I power up and usually 30 secs or so after Im on the desktop itll fade away. The colder it is the longer it takes. The shop said it was OK and so I just left it, but have always had a little nagging doubt about it. Ive never heard anyone elses fans do this. Anyway, recently I installed PC probe2 which shows a warning of the PSU Fan being below the threshhold then just proir to the noise disappearing, then it shows the fan has now kicked in. 

Have any of you experienced this? I'd really appreciate your input.
Thanks, Music.

Pent4 2.4
512MB DDR PC2700 Legend Ram
Asus P4PE 
Thermaltake 360W PSU
Seag 80gig HDD With plenty of free space
Asus 52x42x52 CD-RW
Hyena ATX Case w front USB
External Speedcom 56k modem
Gainward Geforce4 MX440 Graphics w TV out
Phiips 107eFlat Screen Mon
3.5 FDD
Genius Op Scroll Mouse


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## batty_professor (Jul 29, 2004)

It sounds like you PS fan is nearing the end of it's useful life. It's little internal bearing sounds like it's a little dry and worn. But it could possibly run a long time like that. If the noise gets worse, or if the fan quits completey, you will likely replace the supply to remedy the situation. A person with adequate skills could replace just the fan, but having a service tech do it would probably rival the cost of the new PS. The fan itself is a catalog item probably under $5.00 but I can't suggest you tying to do this yourself, as the supply stores voltages, maybe as much as 300 Volts DC. Although if the PS unit was left disconnected from power for a day or two, the voltage should self dissipate to "safe" levels. The fan itself likely is a "plug-in" device in the PS. If you're a "kid" please seek adult supervision. (Your age isn't in your profile).


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## Music (Apr 27, 2005)

Hi, Nope Im not a "kid", (trust me)

I have heard enough warnings about how PSUs holding their charge to steer well clear, and your warning among all the others can not be said enough. 

Now, I'll just re-iterate, this noise happened from the day I bought the machine, and I queried it , but the tech guy said it was normal. It has NEVER changed as in, got louder, etc. It HASNT done it all summer and as we are coming into colder weather where I live, it is doing it again. What I really just want to know basically, is, if I was sold a dud right from the outset or what? I thought Thermaltake had a good name.

Thanks, Music.


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## batty_professor (Jul 29, 2004)

Given what you've now shared with me, it's likely that something, some wire lead, even a zip tie on a small wire bundle perhaps, is contacting the fan rotor in a classic "cat whisker" fashion. It moves with temperature, just enough to make contact when it's cold. And it probably had sufficient clearance when tested in production at the factory. May have took an impact in shipment that moved whatever into contact range. It doesn't sound like anything more than just an inconvenience.


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## Music (Apr 27, 2005)

Thanks for your reply,

So I take it, this is not a normal occurance?

Music.


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## batty_professor (Jul 29, 2004)

Definitely not a normal occurance. The explanation I gave before may not be right-on, but probably not too far off.


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## Volt-Schwibe (Jan 12, 2003)

i'd like to mention some crazy thing....

the fan's bushings are brass, or bronze, and when it gets cold, if there is moisture in the air, it may chatter a bit until it warms up just enough to displace the moisture. (the sound is alot like a humming "vhirrrrrrrrr" sound. the sound batty describes is a fast "buzzzzzz" like a poker card in bike spokes, but the bike's going 55 mhp.)

so, here is what i suggest to tell which it is.

tomorrow, when your computer is cold cold, after sitting all night, unplug it, and aim a hair dryer at the fan on the power supply for a few minutes. (do this on low heat, and keep the nozzle of the hair dryer back at least 10 inches from the computer.)

after about 5 good minutes of mild heat, turn off the hair dryer, and plug the computer back in and turn it on, if it doesn't chatter like normally, then it's probably what's happening. it's no big deal really, but you might want to change out the fan, anyhow.

basically, bushings are made to fail. it's part of their design. so, needless to say, any fan will do it, and it has nothing to do with design quality.


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## Music (Apr 27, 2005)

Thankyou guys for your help and suggestions. 

The noises you are describing could certainly fit the bill....and it seems, nothing is out of the question when it comes to computers. I still reckon a kitchen whizz is a fairly apt description, only not as loud. Also about 8 weeks ago, another problem surfaced which I havnt yet mentioned. This being an extremely hi-pitched whine like a jet engine, but no-where as loud of course. I took PC into the techie and he tested the PSU and blew out a bit of dust etc and said it was OK but I was dubious and as such, installed Asus Probe2 to try and learn a bit more. Anyway back to the other issue, Ive spent hours and hours googling to see if any reviews and such could shed some extra light on this. I did find someone make mention of something similar, but by and large it looks like Im pretty much out on a limb with this.

We are not in actual winter yet and some mornings are still relatively warmish, on and off so Ill have to just wait for the next cold one to come. As I say, its usually happens about 10deg or lower. 

Im pretty sure my PS fan has ball bearings, if that makes any difference ( as you can tell, Im not very knowledgable in this area) and its the model with 2 fans in it. 

..."basically, bushings are made to fail."... 

mmm, if this is the case with mine, then it looks like they sold me a dud. As Ive mentioned, this has been happening right from the outset.

Cheers, Music.


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## ReeKorl (Mar 25, 2005)

One thought occurs: could this be a case of the parts contracting in the cold, then warming up and expanding back to normal size with friction? If so, then it could be the ball bearings are a little too small and have contracted to the point where the fan itself rattles, then expand back to a working size after a few seconds? This would explain the fan not being up to speed until the noise disappears

If this is the case, then the life of your PSU will be shorter than normal (the bearings will wear out slightly quicker) but it's not really something to worry about too much until it actually completely fails (or starts lasting for a lot longer).


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## Music (Apr 27, 2005)

ReeKorl, your thought sounds feasible. Just strange that this isnt a more common complaint, me thinks, from what Ive seen at least. Just re-reading through this thread I thought I might just clarify from my initial post, that around the time that noise fades, PC probe's warning disappears and then the value shows up and the status is OK.

Oh well I'll be certainly keeping my eye on it. Im certainly not confident enough to start messing with a PSU, much less the innards of it. 

Again, thanks for all the input, which is much appreciated!

Music.


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## MD_Willington (Jan 11, 2005)

http://repairfaq.ece.drexel.edu/sam/smpsfaq.htm

Audible whine with low voltage on one or more outputs - shorted semiconductors, faulty regulator circuitry resulting in overvoltage crowbar kicking in, faulty overvoltage sensing circuit or SCR, faulty controller.

Periodic power cycling, tweet-tweet, flub-flub, blinking power light - shorted semiconductors, faulty over voltage or over current sensing components, bad controller.

In all cases, bad solder connections are a possibility as well since there are usually large components in these supplies and soldering to their pins may not always be perfect. An excessive load can also result in most of these symptoms or may be the original cause of the failure.


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