Any ideas what this one is:
Sometimes in the winter, when it gets cold (probably down to 50 or so, but definitely not freezing) I turn on my desktop computer and within 1-2 seconds it makes a loud whining sound, loud enough I can hear it in another room. To stop it, I turn the computer off then on again and the noise does not come back.
I can't figure out what it is. It only happens when it gets cold; now in summer it never happens.