I am taking advice and leaving it to go to sleep naturally after 30 mins but there is still a constant low hum coming from it day and night- sounds like a fan or a hard drive- anyone know why?

Its the fan at the back, close to the ethernet plug.

I already asked the HP support about that but did not get any answere yet (after 2 weeks, guess they are sleeping, at least here in Germany).

Anyone with further information?

Best,

Clem

Cheers
Let me know if you find out please

Never even noticed any noise until I read your post. If I lean very close I can hear a fan faintly but if it's something you can hear in a room with other computers on, you may have a tech support issue. Is your room temp fairly high?

Mine has run 24/7 since I got it a month ago and I've heard others say it is the hard drive. Mine is a cool room (about 68 degrees f) so I don't think it is a heating fan. I assume all of them do this and there is no way to put it to sleep, or is there?

I think it's the hard drive as well. I keep my printer in a cool room and I can't feel any air coming out in the back. If it is a fan, it doesn't produce any air outside the box. Sounds like a hard drive, which should slow down or park itself when not in use for awhile (like a laptop computer does) but this one doesn't.