Here's a little story that caught my eye when I was checking out the news at the Xtra home page that I have on my computer.
http://www.xtramsn.co.nz/technology/0,,7004-2802891,00.html
I for one,know that my computer power supply fan is a bit on the noisy side, but I've more or less learnt to live with it.

Sorry but that link has long gone, but I can't help but think that my hearing is suffering by the High Frequency sound from my computer fans.
As in the CPU fan and the PSU fan.
I've cleaned both of them and the sound is still the same if not worse.
There is a pronounced 1kHz tone coming from the case and I'd invite comments on how to get rid of it.

Mike

Are you sure the sound you are hearing is not coming from the hard drive? Many consumer hard drives do not use fluid bearings and after time can get very loud. I would try disconnecting the CPU fan then starting up the system to see if it was causing the noise you are hearing. Don’t run the system very long with the CPU fan disconnected or you will damage the processor. Also try starting the system with the power cable disconnected from the hard drive. If the noise is still present then the sound is probably coming from the PSU. Check your video card since higher end video cards have small fans that can become very loud over time.

If your system only has 2 fans it should be very quiet. My system is pretty quite but I have 2-PSU fans, 1-CPU fan, 1-video card fan, 3-case fans, 1-7200 rpm hard drive and 2-10,000 rpm hard drives.

Curt

Gidday there Curt,
Thanks for your thoughts.
I know it's not my HDD, it makes a rumbling sound when it bursts into life and only does this every once in a while.
The CPU fan is as quiet as a mouse.
I'm leaning more towards the PSU fan causing all the noise, it's started to make a heck of a racket when I first switch the computer on, in fact not un-like having a horde of angry bees inside the case.
But after the computer has been on for a minute or so, the noise goes away and I'm left with a high pitched tone as I mentioned above.
The PSU is a 400W Enermax and I can't say I've had any problems with it up until this came along.
Wierd, if you ask me.

PSUs are not expensive to replace and any computer shop ought to keep them in stock. But before you do that I would certainly check that it really is the PSU by detatching everything else and running it on its own.

I keep an ageing G3 iMac in the living room purely as an MP3 jukebox. It is probably the last completely convection-cooled, fanless computer there will be. Makes no noise at all except for whichever album it is playing at the time :-)

Trumpy, rumbling from the fan in the PSU probably means dry bearings, especially if it deteriorates to rumble at odd moments then those moments become longer.. and so forth. It's possible to switch out the fan in the PSU, but may not be worth your time as PSUs are cheap. I wouldn't advise most people to go poking around in a power supply, but then most people don't do linework .
A temporary fix may be this .

jooles, chipmunk,
Thanks for your advice, I've had my computer in pieces and it is the fan in the PSU.
I think it could be on it's last legs.
No worries though, I've got plenty of them here that I can use as spares.
Just a little note, while I had the case cover off, I had the TV on in the background, I happened to turn around and look at the screen and it was really messed up with all sorts of Herringbone patterns, I put the cover back on and they went away.
Just goes to show what metallic sheilding can do, eh?
I'll throw another fan in the PSU on my next day off.

"Just a little note, while I had the case cover off, I had the TV on in the background, I happened to turn around and look at the screen and it was really messed up with all sorts of Herringbone patterns, I put the cover back on and they went away.
Just goes to show what metallic sheilding can do, eh?"


That is a sign of a poorly designed system board. I have 2 machines within 6 feet of my TV (one directly under it) and niether cause any problems at all. They are in wooden cases.

The amount of interference also depends on the age and speed of the system. A pentium III 500MHz system is *really* good for messing up UHF tv reception, especially around the 500MHz area...

The core frequency of the CPU is not going to be where the interferance will be. It will be the bus speed. This is limited if the designer has good grounding and signal transmission practices on the board. I would actually expect more noise from the switcher in the power supply. That was where most of the 370 era computer room "noise" came from. That was what most folks didn't understand when they were doing all that bonding. The thing they were protecting the computer from was the computer itself.

I bow to superior knowledge . Yep, the bus being the source would make sense, it's more exposed. I think case design has some bearing as well as motherboard design though, especially with today's very high speeds. One of the nastiest causes of interference I have found is bad grounding. In fact, the level of TV interference from one of my PCs alerted me to the fact that the PSU input connector's ground pin had a bad solder joint
Measuring 120v ac on the case of the PC was scary.
(I traced that to being half mains voltage of 240v from the relatively high leakage filter)

Again, that is a filter to keep the switcher noise out of the power grid, not to protect the computer.

How do you work that out?

quote:
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Again, that is a filter to keep the switcher noise out of the power grid, not to protect the computer.
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How do you work that out?


Something they told me at IBM.

Mike, you can always buy more expensive coolers on the electricity box-side or for the cpu, made of copper.