v … 1 … 2 … v … 1 … 2 … v … 1 … 2 … v
That’s what it’s been like in my office for the last 4 days (a mechanical sound, on the edge of hearing, best described as ‘v’, every 3 seconds). Today I decided to find out where it’s coming from.
After a period of holding my ear next to things (looking stupid no doubt on the cctv) It’s coming from inside one of the computers. I think it’s a regular hard-disk read or something. Can’t be stopped. Damn.
You just don’t have a big enough hammer, obviously.
Perhaps a reboot?
Can’t be stopped? Smack it harder! 
If you’re using XP, it could be that file indexing system they use. I know you can turn that off somehow.
My computer did that for awhile. Then I used some ingenuity. Called the company the had no idea what caused it. So I thought maybe its a vibration. So I stuffed a sock under it to absorb it. Worked like a charm I am noise free.
It could just be a fan, causing some resonant vibration. Mine does that occassionally - but that’s because it’s the wrong size fan and is so only fitted on one side lol.