Ticket #1458 (closed task)

Opened 10 years ago

Invalid fan RPM with variable speed fan on vt8231 (Examined/Solved - lm_sensors 2.8.1 linux 2.4.20)

Reported by: contact Owned by: somebody
Priority: minor Milestone:
Component: hardware Version:
Keywords: Cc:


I'm using a variable speed fan attached to the motherboard fan header on a VIA

EPIA 5000 motherboard.

The fan is an Enermax UC-8FAB which has a speed controller attached permanently.

Sensor is vt8231-isa-6000

With fan1_div = 8 and fan1_min = 1800, I get plausible readings of fan speed

from about 3000 RPM upwards.

If I use the fan speed controller (attached to the fan) to lower the fan speed

below 3000 RPM, I get wildly variable speed readings, either 0 RPM or 163840


Lowering fan1_min to 1500 does not help.

Increasing fan1_div to 16 does not work (not recognised by sensor driver).

John Allen

Bofferdange, Luxembourg

allen@… --- the fan controller may be injecting noise onto the tach lead,

or the tach lead may not work correctly when the fan controller

is active. You may wish to look at the fan controller documentation

or look at the tach lead with an oscilloscope.

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