My desktop making noise

open up the side panel and verify that the fans are not rubbing on any wires   if not then either your hard-drive is getting old and may need to be replaced before you lose your family photos and documents   or if the main board is beeping then it is a beep error code   listen carefully to the pattern and look up beep error codes for that make of computer

Hello there:
this is generally due to a fan that is either dirty and needs to be cleaned or has worn out and needs to be replaced.
If it is a continous clicking sound this is generally a harddrive that is failing and needs to be replaced or serviced .
Open the left side and remove the cover and start the computer and listen closley and you will be able to pinpoint where the noise is coming from ok?
Please keep me informed on what you have discovered so i can give you some more advise if needed ok?
I hope that this has been very helpfull for you !!
Best regards Michael