My PC has developed a problem. When I am doing anything that takes a lot of power (like games at a decent resolution), my system will lock up and I can hear a squealing sound from around the cpu. This lasts about 10 seconds and happens about once every minute. It takes less stress to happen when it is hot in my room. When not under heavy load, it is fine. I have ruled out about everything except the motherboard and cpu. It is easy to pinpoint to around the cpu area. It is not caused by fans or my hard drive, or the warning speaker, and my power supply is in the bottom of my tower, away from the cpu. It is my understanding that a bad capacitor can make a squealing sound, so I am about ready to purchase a new motherboard. I just wanted someone else's opinion before I spent money. Thanks to any who can help.

Have you checked the system temperatures?

sounds like a fan or hard drive making the noise, or a optical drive if there is anything in it, but id bet its the fan because of higher heat. check the temperatures in your computer and it could also be the cpu fan not a case fan, possibly the bearings are broken.

Thank you for the replies. The cpu gets up to a max temp. of about 59 C under worst case.
(I understand this is a bit hot, but this is worst case) It is not a fan, since I have manually stopped every one while the noise continues. It is not any type of drive. I have set the hard drive aside, out of the case, and unplugged all drives and the sound still comes from around the cpu area. If the system temp is getting too high, I can understand problems, but I would like to know the specifics of the squealing sound + system freeze. If system temp is getting too high, I'm not sure of anything I can do. I have a Swiftech heat sink with 80mm fan on the cpu and plenty of case fans.

You may have a capacitor failing..

Keep the old stuff running

Capacitors do not normally make any noise, and it is only the electrolytic ones (in tiny cans) with liquid inside that can do that at all.
If they do make any noise, it would be a popping or hissing or squealing noise, usually only once in the case of a popping noise, maybe a few times in the case of a hissing noise, then the capacitor would be dead or blown apart, and your mboard (or power supply) may not work at all after that.
You could examine the mboard's capacitors (the ones in tiny cans, usually upright)for bulging tops or leakage of fluid or dried fluid around them, but it's very unlikely you have that problem. The defective capacitors that did that were on mboards made from about 2000 to 2003 - if your mboard is newer than that, it is extremely unlikely your have any bad capacitors on the mboard, but you could have them within the PS.
Defective PSs are common.
Check your PS.
See response 4 in this:
http://www.computing.net/hardware/w...

Since it's unlikely you have stopped the PS fan from turning, it's probably the bearings in that fan that are making the noise. The fan is a standard size and easily replaced - get one that has the same wattage or amperage rating or higher and that should push a similar or better cfm rating.
Rarely, a hard drive will make a high pitched squealing noise (e.g. Western Digital drives can do that), and if it does that's almost always not a good thing with fairly recent hard drives - it will fail eventually, probably in a short time.
check your hard drive.
See the latter part of response 1 in this:
http://www.computing.net/windows95/...
If you don't have a floppy drive, you can get a CD image diagnostic utility from most hard drive manufacturer's web sites, but obviously you would need to make a burned CD, preferably a CD-R for best compatibilty, on another computer if you need to.

It is often hard to pinpoint exactly where a sound is coming from within the computer case.

I don't know what is causing the noise you hear. I suggest using a mechanics stethoscope to isolate the noise. If that isn't available a short piece of rubber hose or tubing placed to the ear, with the other end held near the suspected component.

Good suggestion OtheHill.