|Are you absolutely certain it's coming from a fan? It "might" be coming from the hard drive... Clicking sounds from a drive mean it's on its way out... Likely to go any time...|
Until you actually discover the cause, I'd be inclined to safeguard - as in duplicate/copy - "all" your personal files etc. to external media. Typically DVD but another (external) hard drive too is nice(r).
Doing that means that "if" the drive is going down, then when it finally does... your files at least are safe elsewhere.
You might even make a complete backup of the drive (operating system and apps - and anything else there) again to DVD. Doing this means that you will be able to re-install the image to a new drive in due course. But likely you will need to re-activate the OS.
Not being at familiar with win-10 (and I have no intention in that area until it's been somewhat debugged...), I don't know what backup utilities are included in win-10. There are third-party imaging apps that likely will do it too; Acronis and Easus being two that come to mind?