Solved CPU fan regulation at QNAP TS251+

Hello everybody,
Does anybody know how I can manipulate the fan rotation speed at my homeserver? Specs here.
With FreeBSD installed the fan always rotates at maximum speed which is annoying due to the noise...
1. How can I monitor the fan regulation speed?
2. What is the FreeBSD equivalent of sensors-lm (in Linux), which shows you all sensor values of the device?
3. How can I manipulate the fan rotation speed depending on the processor temperature?

The processor is passively cooled and the fan known by the BIOS as CPU fan is a case fan producing an air circulation near the processor to cool it down .
Fan speed is usually controlled by the hardware depending on CPU (and/or other) temperatures. If you haven't already, use powerd(8) to make the CPU run cooler. Try # powerd -a adp and see if fan slows down. You can check the CPU temperature by # kldload coretemp and then sysctl dev.cpu.0.temperature. This can be made permanent also.
Typing on phone, enough for now...
Hi k.jacker, Thx for your message. "powerd" is already installed and active - # powerd -a adp gives me the pid of the process. Under Linux I had to detect all sensors manually before I could get reliable values from all sensors installed - Is such a detection not necessary under FreeBSD or is it done automatically during installation? Thx
There is no "all sensors in one tool" in FreeBSD. As with coretemp.ko I mentioned above, this is a loadable kernel module that provides access to the temperature sensors inside of Intel CPUs.
An equivalent for AMD CPUs exists as well. That's how it works in FreeBSD.
Is such a detection not necessary under FreeBSD or is it done automatically during installation?
Such things don't happen on FreeBSD. You can (and have to) make all choises yourself. If you want to read sensor data, you have to check what you need (coretemp.ko in your case for the CPU) and set it up.
Every kernel module/driver, every tool and even most config files have their own manpage.

Most important thing for me is to read CPU temperature and frequency as well as hard disk temperatures.
CPU temperature can be read as I explained in my first post.
CPU frequency is in sysctl dev.cpu.0.freq
Hard disk temperatures can be read using sysutils/smartmontools (along with other SMART data, selv tests, etc.)

Many kernel modules, after they have been loaded, add new values to be set and read to the tool called sysctl(8).
You can sysctl -a or sysctl -a|grep temperature before and after you run # kldload coretemp to get an idea of what I'm talking about.
Yes, CPU temperature and frequency works well. But fan speed is a different matter. it depends on the board and chipset.

In my case (intel core2 B75, ASUS board) I did not yet figure that out, although it is visible in the bios. The chipset specs (C216, available from Intel) say that only the server/workstation design has fan monitoring capabilities, so I don't know how it may work on a desktop.

What is definitely interesting for these intel chipsets is the sysutils/intel-pcm port, which shows many more info (will be even more on a real server chipset), but I didn't find fan information there either.

Then, concerning the original question: manipulating is again a different thing than monitoring - but there is always the option to get a fan that is temperature sensitive on it's own, or to add a temperature sensor to a normal fan (should be available for some 2$), and then run the fan directly from PS 12v.