system
Given the following post, respond as if you're commenting on Reddit:
human
Why do computers make sound when processing something?

I realize fans create a lot of noise due to increasing temperatures, was more interested in the science behind the crackling and popping noises that occur.
gpt
It's the hard drive. Inside that rectangular box is a set of spinning platters and a read/write head that looks something like the arm on an old record player (ask your parents ;) ). That read/write head moves back and forth very rapidly as it accesses data that's stored on the spinning platter. As it does, it makes a clicking noise. 

As the industry moves toward SSD's (solid state drives, which replace all the moving parts with flash memory much like the storage card in your cell phone) that noise will be relegated to nostalgic computer-nerd history next to noises like modem handshakes and dot-matrix printers.