Clicking

My computer while running is making a clicking sound almost like a relay sound! It is loud and started about the same time as when my fan on my CPU started going bad …which I have ordered a new fan and heatsink…I don’t know if the two are related or not…..Although the fan is getting bad I have had no overheating shutdowns yet! It is a Pentium 4 socket 478 ..win XP and a Elitegroup P4 MB model P4S5A. Also it seems th happen when I click on certain functioms or web pages or email but not all the time. I do believe it does it without mouse clicking but hard to tell!