For the average PC, most of its noise comes from its fans. Computers are typically built with cooling fans that are meant to operate at acceptable noise levels. Although, as machines age, they tend to require more work out of the installed fans in order to keep the components cool, which may explain why your old machine is much louder today than when you first got it.
EZ MSP Blog
EZ MSP has been serving the New York area since 2008, providing IT Support such as technical helpdesk support, computer support and consulting to small and medium-sized businesses.