Noises on older iMacs

Hello. I have an iMac 2009 with Yosemite, 12gigs memory. It’s now making 2 sounds - clicking and buzzing. The sounds surface periodically. Do you think it’s the fan or something else? Been working fine. Installed new internal drive 1 year ago.

SSD or HDD? Clicking sounds are often the sign of a failing HDD.

HDD. Thank You.