[lm-sensors] w83627ehf-isa-0290 CPU fan rpm: wrong value

simone marchi simone.marchi at ilc.cnr.it
Thu Sep 14 11:26:44 CEST 2006

David Hubbard ha scritto:
> Hi Simone,
> This is a hardware problem that has no easy solution. I believe you
> have fans with three pins and three wires. (If the fan that is giving
> you the wrong value is a four-wire fan, then this must be something
> else.) Three-wire fans get an RPM count while the power is being
> rapidly turned on and off. It can cause this kind of behavior.
> Hope this helps,
> David

Hi David,
thank you for your support!
My fan has three pens and three wires. I'm using the bundled fan with my
athlon64 3800+.
I've tried to do a simple (dangerous) hack of w83627ehf source code:
I've substitute all occurence of
w83627ehf_read_value(client, W83627EHF_REG_FANDIV1)
with the vale 4 (that works fine for me).
I know that can be very dangerous because I'm not kernel expert!
But it works fine!

So, I also tried to patch my kernel (2.6.18-rc6) with
to gain fancontrol also.
With this patch I can successfully controll my fan and get correct value
for rpm fan speed.

A simple report about fancontrol:
the pwmconfig configurator fails sometime and it says "no correlation".
But, if I try other times, it works fine and I can get fan control (with
pleasure :) )
The Q-fan2 Bios feature (by Asus) must be enabled or disabled ?

thank you
ciao simone

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