Humming noise

[Steven60]

I recently purchased a HP All-in-one PC.

When I turn it on, you can hear the fan working, which then slows down and runs continuously (at about 30%). This results in a low (but noticeable) humming noise. 

The PC is not hot and, other than the humming noise works perfectly.

I have done the normal stuff - i.e. ensured that it's on the latest BIOS, ensuring vents clear, etc

Is it normal for the fan to run continuously at around 30%?

[savvy2]

so you just bought this PC used?, and so do not know all PC air cooled have fans.?

and all CPU make heat, even doing zero work on the desktop , and that means the fan must turn, if not the CPU will overheat.

if this PC is old and you had it a long time and just now today , the PC humms, that is a bad fan.

that is my answer regardless of history,  I hope I saved you huge time wasted.

all PCs with fans make noise, and the data sheet on most PCs even show the Acoustic  noise spec.

Abnormal noise is purely a hands on thing , by any experienced tech. All fans have bearings and all go bad.(old)

or are packed on lint and makes a racket, we simply clean those.

good luck finding noise. some are a challenge, for sure lose parts inside once dropped, hard.

I say get a shop to check it  out,  for any noises.

[Steven60]

Thank you.

I purchased the PC brand new.