If you aren't getting the expected readings on your fans,
try the following:

- Do you get a fan reading in the BIOS or in DOS?
  If not, you may not have a fan with a tachometer output.
  Look and see. Fans with tachometer outputs have THREE wires.

- Try experimenting with the fan divisor settings:


Fan Divisor	Minimum RPM	Maximum RPM

  1		5314		1350000
  2		2657		 675000
  4		1328		 337500
  8		 664		 168750
 16		 332		  84375
 32		 166		  42187
 64		  83		  21093
128		  41		  10546


Pick a divisor so that the nominal RPM is about 50%
above the minimum. This is a good compromise between
margin and accuracy. Note that most chips only support
fan divisors of 1, 2, 4, and 8.

If you have a 0 RPM reading some or all of the time,
increase the divisor until you get good readings.

If you have a nominal reading less than 1.25 times the
minimum, increase the divisor to give you margin
so that you will not get spurious alarms.

If you have a nominal reading more than 3 times the
minimum, decrease the divisor to provide better
accuracy.

- How to change fan divisors:

  Method 1: "echo x y z > /proc/sys/dev/sensors/...../fan_div"
  where 'x y z' are the fan divisors for the three fans and '...'
  is the sensor in question.

  Method 2: Put an entry "set fanx_div y" in the appropriate section
  of /etc/sensors.conf and rerun 'sensors -s'.
  (x is the number of the fan 1-3 and y is the divisor).