Nasty strong hum from mac mini possibly combined with UPS

Thanks a lot den.thed

Well, never... And that makes me realize we have had to unmount an electronic piano a few months ago to clean it and stop another kind or electronic problem, after 3 years in a large city where the dust was heavy in the appartment... You would clean and the next day see a layer of dust on furniture.

You may be right. I heard not so different noises on You Tube for mac mini needing cleaning. Although when I hear the fan running high on startup on mine, the sound of the fan itself appears ''normal''. But perhaps at low speed it would remain the culprit of that constant noise which, again, is very diffuse - to the point I never notice in several months it was caused by the mac... Being located tight in a corner shaped by a wall and furniture, that may indeed take a tiny noise sound bigger, diffuse and lower frequency than typical fan. The mini also get very warm for no reason (logged off!) at times. I never shut it down (well now I do it since yesterday now that I realized).

It also stands on a fan without its cap with the fan ''pulling'' warmth down when needed (when I do stuff like video rendering or heavier audio work). (No, no it's not ON when I hear the noise - no not caused by this fan).

I watched cleaning on M-based macs, hopefully it's not more complicated or risky on the 2018 - I know what I'll do in coming days. I still have doubts as this new construction here is a little weird with electrical circuits (can you believe that if my son connect his macbook for recharge, because both rooms are on same breaker, it jumps out ? He has to connect it in another room. This is why I first thought of an interference)

UPDATE : I tried it in another power bar, avoiding the UPS, and the rotating hum is still there. So troubleshooting must be within the mini