Computer making odd noises

[daltonls]

The past couple of weeks, my computer has been making unusual noises which don't seem like they should be sounding. I hear them mostly when I'm starting up, and a few minutes after it's done starting up. They mostly sound like something in the computer is vibrating against something else, or is just being very loud for some reason. Should I be concerned with it and take the computer somewhere to be checked out? That's basically my question.
And sort of a secondary question is an arguement between myself and a friend of mine. He thinks these sounds could be caused by a virus, but I don't think that a virus could affect something like that. So who exactly of we two is right?

[Ankerson]

A virus can't make those sounds happen so that's not it.

A vibrating sound could be cased by a fan.

Shut down the computer and take the side off the case.

Get some canned air and blow out all of the vents and fans in the case including the Power Supply making sure you get all the dust out.

Turn the machine back on with the side of and see if you still hear the noise. If you do then you should beable to tell where it is coming from.

[Crashman]

It sounds like a loose, dry fan bearing. The loosness causes it to vibrate, and the dryness causes it to rotate choppily. Put the two together, and the fan will "growl" until it gets warm enough to melt the remaining dried out oil.

Eventually the fan will quit. You need to locate it right away and replace it. If it's a difficult to find fan, you can try oiling it to extend the life, but it will still be somewhat noisy.

[Sterling_Aug]

The only important factors with replacing fans are size and air flow.

When you replace a fan, you should get the same size unless you have room and the mounting holes to go bigger.

There will be many different air flow amounts for each size fan. The more air, the more noise (louder) a fan will be.

[Crashman]

I mentioned "difficult to find" fans because chipset and graphics coolers usually have fans that don't match up to what's widely available on the market.

[G Ray88]

How old is your computer?
Good Luck

[tcom50]

What IF Its a cpu FAN.................Do you have a program to give you fan speeds??

[Blake22]

Make sure you don't have a CD in the CD_rom, this can sometime make the noise.

[rmanet]

Ankerson's right - open the case and listen carefully after cleaning it out. You usually only have the power supply and CPU fan - neither should be making other than normal sounds.

Fortunately it does sound like a fan - make sure it's not a clicking or loud whirring or spinning up and down noise on the HDD. if it is, back it up and get a new one pronto. Blake's also right, a failing cd drive or bad cd will usually give you a nasty rattling noise while the thing is banging around in there at high rpms.

[daltonls]

It did turn out to be the fan which was causing the problem. It was very dusty, so it wasn't running very fast, and even after cleaning it out well with some canned air, it was still running too slow. Had to replace the fan, so it's working fine now.

Thanks to everyone for your help