So my 3 year old harddrive is making a weird noise, a slight clicking but its not very loud, it can hardly be heard but its still there. Smart says the hdd is 100% healthy but the noise worries me, does it mean its going to be damaged?
It depends a bit on what kind of noise it is, it could just be normal harddrive activity (caused by software running in the background, Windows indexing, or perhaps a fragmented harddrive?)
Have you tried running chkdsk on the drive? Also you could try to defragment the harddrive and check if you have any problems running in the background that might cause a lot of harddrive activity like a antivirus etc.
And of course always make sure you have a good backup on an external media of any important data you have on the system!