Philip Ashmore wrote:

> Hi there.
> 
> I managed to record it using my laptops built-in microphone.
> 
> To those who would prefer a description:
> It starts fast and slows down. I opened the file with Audacity and
> determined the intervals to be 0.1, 0.3, 0.6, 10, 15 seconds, then it
> repeats.
> 
> It sounds like some kind of protocol negotiation algorithm that requires
> a disk sync when the polling time doubles.
> 
> Here's a link for your listening pleasure:
> https://www.dropbox.com/s/apdr1o056tam5ie/click.wav?dl=0
> 
> I'm hoping it's some cron job, or DropBox, Trinity Desktop, wifi, smart
> disk status monitoring, nVidia, Intel, ... not a virus trying to phone
> home.
> 
> I'm really hoping that someone reading this will go "oh that thing" and
> know what it is instantly.
> 
> Curiously it doesn't happen every day.
> 
> Regards,
> Philip Ashmore

You can try a hard drive test and/or smartctl and see what it reports. It
sounds like a head is clicking here and there - so definitely a mechanical
thing. Recently 2 friends came to me with broken disks - saved/lost 1:1.
Make backup!

regards