My computer makes a loud, high-pitched, very unnerving noise! Help!

[Illuminatus42]

When I turn the switch on my computer's power supply to on, the computer starts making a, like I said, loud, high-pitched schreeching noise. My first guess is that something awry with the power supply itself. Any other ideas of what might be the problem? And what I am to do to stop it?

[DeltaSlaya]

When I turn the switch on my computer's power supply to on, the computer starts making a, like I said, loud, high-pitched schreeching noise. My first guess is that something awry with the power supply itself. Any other ideas of what might be the problem? And what I am to do to stop it?

This may help:
http://www.computerhope.com/beep.htm

[Illuminatus42]

Thanks for the tip, but it's more of a long screech that goes up and down irregularly in pitch.

[street1 (RIP)]

Well, a fan bearing in the Power Supply Unit
could cause this.

Can you block the fan from turning for a few seconds
plastic spoon handle etc...

Turn on the computer then see if it screeches.

[patio]

Actually you might want to remove a side panel to better determine which fan is doing this...if it's the vid card fan or the CPU fan you risk damaging expensive components...

DO NOT continue to run the machine in this condition.

[Illuminatus42]

I don't think it's one of the fans, since the noise starts when I flip the little power supply switch on the back of the computer to on. So the noise starts before any fans are on.

Thank you street1, I'll try that.

[Joe_Flanagan]

I had this happen recently.
It was a screeching sound and I believe it was coming from the mobo speaker.

After starting the machine with minimal components, then adding them back one by one, it turned out to be a defective floppy drive.

Perhaps,what I was supposed to be hearing was a long continuous beep.
It just sounded more like a screech.

[patio]

I don't think it's one of the fans, since the noise starts when I flip the little power supply switch on the back of the computer to on. So the noise starts before any fans are on.

Thank you street1, I'll try that.

I'd still check the fans...

[Illuminatus42]

I don't think it's one of the fans, since the noise starts when I flip the little power supply switch on the back of the computer to on. So the noise starts before any fans are on.

Thank you street1, I'll try that.

I'd still check the fans...

I did, I stopped them for a few seconds. No change. The sound is more... electronic. And it's not a clear tone, it's... more of a schreech-scratch-ish sound.

[patio]

You checked ALL fans ? ?

Vid card fans screech when they're dying...you may have overlooked it if the fan is on the underside of the vid card.

[Illuminatus42]

Yeah, the fans on the power supply, the fans on the CPU and mobo, the one on the chassi and the one on the graphics card. No effect on the noise. Besides, the noise starts long before any fans are running. Like I said, when I flip the switch on the back of the power supply, the noise starts. So I guess it's either my power supply or my mobo. 

I also tried removing my sound card, my RAM, one of my harddrives and my graphics card. It still screamed.

[DeltaSlaya]

I don't think it's one of the fans, since the noise starts when I flip the little power supply switch on the back of the computer to on. So the noise starts before any fans are on.

So are you saying the noise occurs even when the computer is not powered on? It happens when the power supply is on but not supplying current to components, except to motherboard.

[Illuminatus42]

That's exactly what I'm saying, but the thing is the noise is just... too high - and it doesn't stop. It's been like this for a week or so now.

[DeltaSlaya]

That's exactly what I'm saying, but the thing is the noise is just... too high - and it doesn't stop. It's been like this for a week or so now.

In that case try turning off and unplugging the power supply. Open your case and make sure you ground yourself by touching the case or using a grounding bracelet. Then unplug all the cables that are coming out of the power supply. Plug the power supply back in and turn it on. Does the noise still occur?

Also, you never mentioned if the computer in question still loads and runs an OS?

[Illuminatus42]

I'll try that tomorrow, then. Yeah, it works perfectly as usual, Windows XP. The only problem is the noise.