IPMI Fan Sensors
Jul 16, 2015

I orded two Noctua NF-A14 industrialPPC-3000 fans for the front intake of my server to cool hard drives. Unfortunately, they are extremely loud at max RPM even with the case closed and the closet door shut. Because of this I wanted to use fancontrol on Debian to lower the fan speeds. This did not work and I was left with setting the fan speeds through the Supermicro IPMI web interface.

After setting the “Fan Mode” to “Standard Speed”, the fans would drop to low RPMs but then ramp back up to full speed due to the RPMs dropping below the fan threshold. This was quite annoying and needed to be solved. Supermicro appears to set the lower fan RPM threshold to around 600 RPM and when the Noctua fans drop below that (which they can, easily) it ramps them up to the max because it’s techincally an “emergency” (a.k.a. fan is offline). To fix this you have to lower the RPM threshold so they do not ramp up.

The Noctua industrial fans are connected to FAN2 and FAN3. They generally don’t drop below 800 RPMs so I set the thresholds slightly higher than the other two standard Noctua fans (FAN1 and FANA). FAN4 has nothing connected to it.


apt-get update && apt-get install ipmitool
modprobe ipmi_devintf

Lower Threshold

ipmitool sensor thresh FAN1 lower 100 150 200
ipmitool sensor thresh FAN2 lower 200 250 300
ipmitool sensor thresh FAN3 lower 200 250 300
ipmitool sensor thresh FANA lower 100 150 200

After this you should power off the machine and turn it back on. For some reason it still had the ramp down and ramp up problem until I shutdown and booted.