I'm facing a weird problem here.
I have a Zotac box, 1.6 GHz Atom, nVidia ION. I used it as a MythTV frontend for some time running Gentoo. It worked great, when load (and temperature) went up the fan revved up, too.
Now a friend of mine needs a small box with HDMI output, so I was about to give this box to him. He obviously cannot manage Gentoo (not to mention portage is on NFS - on my LAN). So I installed Lubuntu for him.

Problem: The CPU fan runs at low speed at all times, regardless of load.

Can anybody suggest a solution?

did you make cpu stress test? there is web based stress test, just google for "online multicore cpu stress test"

you can run on your machine mostly any distributed computing project like folding@home so you can see if machine is actualy overheating

Fan control is usually done by the mainboard, not the OS. Have you changed BIOS settings that may have caused that behavior?

Thanks for replies.

As a matter of fact everything went back to normal after hard reset (power unplugged for a minute).