What's that noise inside my computer?
Dear Straight Dope:
Hey, Cecil, just what exactly makes that rapid-scratching noise inside your computer while it's processing your programs? If there are no moving parts, is it just the electricity being shredded around?
Deep inside the nether regions of your computer is a Hard Disk Drive. And it does move. The new HD I just added to my system spins at 5400 rpm. But that's just a high pitched whine you'll never hear unless it's coming up to speed or winding down. What you most likely hear is the read/record heads reading the magnetic 1's and 0's that your programs and files have placed on the disk.
And let's not forget the cooling fan for your tower either, and the little fan on your processor chip. And of course there's general electron whine. That's why you're supposed to grease the wires occasionally.