HP Proliant Microserver case fan

For starters: I found a great review on silent PC review for the Microserver. It gets some pretty good reviews: http://www.silentpcreview.com/article1193-page1.html

There is however something small that annoys me: the fan in this case keeps on running at minimum 1000 RPM. This is strange since the CPU is passive cooled. Also the temperature stays around 30°C, which is very low. Wondering if I could get it down. I mean if the disc is not spinning and the CPU is passive cooled, why is it running?

But seems like I won't be able to do it from software since the sensor is not under software control. It is mentioned on this forum: http://www.silentpcreview.com/forums/viewtopic.php?f=20&t=60236
But I'm still waiting for final confirmation of that from HP. This guy asked the same question I wanted to, see if it gets a response: http://h30434.www3.hp.com/t5/Other-HP-Consumer-Products-and/HP-ProLiant-Microserver-N40L-fancontrol-with-Debian-6/td-p/1228957

Another option is to go hardware :-)
The following article talks about installing another fan. But I guess I'm not that desperate yet.
http://www.silentpcreview.com/article1193-page7.html