PoE HAT - noisy fan

[Juggler00]

I have the official Raspberry Pi PoE HAT and am running a fully-updated Raspbian. I am noticing that the fan on the PoE HAT is very noisy. It appears to spin up to 100% every 10-20s, run at 100% for ~60s then repeat.

I did some searching on the forums and have seen some comments on how to alter this behaviour. I’m looking for the actual, proper way to do this. Can anyone help?

[ShiftPlusOne]

Out of curiosity, what's the ambient temperature of the room and what's the pi doing when the fan kicks in, if anything?

Edit config.txt and add the following line:

Code: Select all

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000,poe_fan_temp1=82000,poe_fan_temp1_hyst=2000

That should change the behaviour so that the fan turns on at 80C, turns off when it comes back down to 75C. If the temperature reaches 82C it will go full blast until it drops back down to 80C. You can play with the values and adjust them so that they suit you.

https://github.com/raspberrypi/firmware ... ADME#L1649

It appears to spin up to 100% every 10-20s, run at 100% for ~60s then repeat.

It shouldn't go to 100% right away, but let's check if the instructions above help before diagnosing further.

[Imperf3kt]

I thought the fan could only be controlled between 60 and 70 degrees. Is it now possible to force it to any desired value?

[ShiftPlusOne]

The behaviour of the fan could always be defined by the user. The most recent change (a few months back) was to make the temperature and hysteresis values easily adjustable through config.txt, to cover most use cases without having to rebuild a device tree overlay.

[Juggler00]

The room is at 21ºC, so nothing extreme. I'm running ser2net on the Pi so that my instance of HomeAssistant sees the USB z-wave stick attached to the Pi as a local device. This does increase the network traffic, so I'm wondering if that could be causing the "freak out"?

I've made the changes to config.txt; so far so good. Thanks!!!

Out of curiosity, what's the ambient temperature of the room and what's the pi doing when the fan kicks in, if anything?

Edit config.txt and add the following line:

Code: Select all

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000,poe_fan_temp1=82000,poe_fan_temp1_hyst=2000

That should change the behaviour so that the fan turns on at 80C, turns off when it comes back down to 75C. If the temperature reaches 82C it will go full blast until it drops back down to 80C. You can play with the values and adjust them so that they suit you.

https://github.com/raspberrypi/firmware ... ADME#L1649

It appears to spin up to 100% every 10-20s, run at 100% for ~60s then repeat.

It shouldn't go to 100% right away, but let's check if the instructions above help before diagnosing further.

[80ov]

The behaviour of the fan could always be defined by the user. The most recent change (a few months back) was to make the temperature and hysteresis values easily adjustable through config.txt, to cover most use cases without having to rebuild a device tree overlay.

On what the kernel does it work? I have 4.14.9x. After adding a line

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000,poe_fan_temp1=82000,poe_fan_temp1_hyst=2000

in to /boot/config.txt - raspberry did not boot after reboot.

[ShiftPlusOne]

On what the kernel does it work? I have 4.14.9x. After adding a line

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000,poe_fan_temp1=82000,poe_fan_temp1_hyst=2000

in to /boot/config.txt - raspberry did not boot after reboot.

Should work on all relatively recent kernels.

I've just tested it with rpi-update a08ece3 (4.14.98) and it seems to work.

Unrelated to this, but I've just noticed that config.txt dtparam lines seem to have a character limit. poe_fan_temp1_hyst=2000 is cut off, so you may wish to split it into two lines:

Code: Select all

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000
dtparam=poe_fan_temp1=82000,poe_fan_temp1_hyst=2000

[80ov]

On what the kernel does it work? I have 4.14.9x. After adding a line

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000,poe_fan_temp1=82000,poe_fan_temp1_hyst=2000

in to /boot/config.txt - raspberry did not boot after reboot.

Should work on all relatively recent kernels.

I've just tested it with rpi-update a08ece3 (4.14.98) and it seems to work.

Unrelated to this, but I've just noticed that config.txt dtparam lines seem to have a character limit. poe_fan_temp1_hyst=2000 is cut off, so you may wish to split it into two lines:

Code: Select all

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000
dtparam=poe_fan_temp1=82000,poe_fan_temp1_hyst=2000

Great, it worked!
Спасибо!

[ShiftPlusOne]

Great, it worked!
Спасибо!

Glad to hear it.

Незачто!

[Toorms]

Hey Community,

I'm a little bit confused right now. For what we have two fans in the config file? fan0 and fan1 - usually the PoE HAT has only one fan on top of the HAT.

Code: Select all

dtparam=poe_fan_temp0=60000,poe_fan_temp0_hyst=3000
dtparam=poe_fan_temp1=65000,poe_fan_temp1_hyst=3000

Can anybody explain this? Thanks.

[rpdom]

I'm a little bit confused right now. For what we have two fans in the config file? fan0 and fan1 - usually the PoE HAT has only one fan on top of the HAT.

I cant see two fans in that file. Just one fan with two different temperature trigger points.

[bpaoz]

Like the OP I have 3 x Raspberry Pi 4 units with official POE HAT modules to act as home automation radio bridges throughout a house and find the noise generated by the fans to be very loud. The workload of running ser2net or usb/ip isn't much and even just a base operating system install without any connected users causes the POE HAT fan to spin up for 15 seconds every 50 seconds.

The configuration settings discussed in this thread do work, but eventually the fan has to go on to cool the SOC at some point and the sudden noise is so noticeable that you cannot put the Pi in any room where people are likely to be. I'm unsure what use case was envisaged for the POC HAT as designed, as every other POE device I have deployed here at home is completely silent (ie IP cameras, wireless access points etc).

Is there some way to switch the fan permanently on, perhaps at a very low RPM so it makes less noise?

Alternately has anyone had success replacing the fan with another model that perhaps isn't as noisy?

Or has someone found some settings / configuration / workaround where the fan won't switch on and it doesn't fry the Pi?

I'm happy to buy extra parts to solve this as I'd really prefer POE to work. But I've ordered conventional heat sinks, cases and USB power supplies given the POE HAT doesn't seem feasible if you need the unit in a typical household room.

[bpaoz]

A short update following further research today.

The fans inside the official POE HATs that I have here are Sunon MF25060V2 units (data sheet). The rated noise is 18.0 dB, and I couldn't readily find on Mouser Electronics any compatible replacement fans at a materially lower rated noise.

Fortunately there may be a software solution though. The existing rpi-poe overlay provides 3 temperature setpoints which operate the fans at 0, 150 and 250 PWM. Pull request 3493 adds a further 2 temperature setpoints at 31 and 63 PWM.

Hopefully a merged PR 3493 will resolve the issue of lightly-loaded Pis being cooled sufficiently.

[jahboater]

Like the OP I have 3 x Raspberry Pi 4 units with official POE HAT modules to act as home automation radio bridges throughout a house and find the noise generated by the fans to be very loud.

Are you running the latest Raspbian updates?
The recent firmware keeps the temperatures very low and there should be no need for any forced cooling with any load.
What does the load average look like (uptime) and why is it getting so hot?

This cheap (£1.57) stick on heat reduces the temp further (mid 60C's running the cpuburn stress test) and is silent of course.
https://uk.rs-online.com/web/p/heatsinks/7500951/

I have just tried this little case:
https://www.mechatronicsart.com/mechatr ... nclosures/
which reduces the cpuburn temp down to around 56C.

For light loads the temp remains in the 30C's

[bpaoz]

Are you running the latest Raspbian updates?

Raspbian Lite 2020-02-14 (kernel 4.19.97-v7l+).

What does the load average look like (uptime)?

Code: Select all

 08:06:49 up  1:44,  1 user,  load average: 0.00, 0.00, 0.00

Why is it getting so hot?

The official POE HAT covers the entirety of the Pi and this impedes both convection cooling of the SOC or the introduction of a passive heatsink. So you are reliant on the POE HAT fan, and unfortunately it's noisy at the PWM settings in the currently-released overlay.

However am pleased to now confirm that PR 3493 comprehensive resolves this issue.

[manuel]

Wow, this is great. Now the fan rotates on a very low noise level

[Squuiid]

Is it just me or does this fix no longer work on a fully up to date buster Pi OS install?
I've tried two Pi 4s now, where this fix previously worked fine, but no longer.
Any ideas?

UPDATE:
Never mind. Found the fix. There were changes to the kernel which mean you now require setting 4 parameters instead of just two.
https://github.com/raspberrypi/linux/pull/3493
This works with latest kernels:

sudo nano /boot/config.txt

dtoverlay=rpi-poe
dtparam=poe_fan_temp0=70000,poe_fan_temp0_hyst=1000
dtparam=poe_fan_temp1=75000,poe_fan_temp1_hyst=5000
dtparam=poe_fan_temp2=80000,poe_fan_temp2_hyst=5000
dtparam=poe_fan_temp3=82000,poe_fan_temp3_hyst=2000

[ktrainor]

Hi Squid,

Thanks for posting this solution. It has definitely quieted down the fans on my budding Pi 4 cluster. I will need to load it up in order to give it a full test. Thanks again.

Kevin

[revv]

Squuiid's solution worked on my Raspberry Pi 4 with PoE HAT. My fan is now off, but my temperature has climbed to 54-55 from 40.

Can anyone explain to me what these variables do?

dtoverlay=rpi-poe
dtparam=poe_fan_temp0=70000,poe_fan_temp0_hyst=1000
dtparam=poe_fan_temp1=75000,poe_fan_temp1_hyst=5000
dtparam=poe_fan_temp2=80000,poe_fan_temp2_hyst=5000
dtparam=poe_fan_temp3=82000,poe_fan_temp3_hyst=2000

I get that poe_fan_temp0 throug 3 are temperatures in celcuis (I'm using 60000, 70000, 80000, 82000 instead of the above).

If I wanted to have my fan turn on at a very slow speed at 45 degrees and keep it on while it is above that temperature while increasing as temperature climbs, is poe_fan_temp0_hyst the variable to change? If so, what are those values? RPMs?

[Squuiid]

https://github.com/raspberrypi/firmware ... ADME#L2128

[revv]

Got it.

So, if I'm interpreting this correctly, the fan has 4 states plus off state:

dtoverlay=rpi-poe
dtparam=poe_fan_temp0=70000,poe_fan_temp0_hyst=1000 <-- Lowest fan speed
dtparam=poe_fan_temp1=75000,poe_fan_temp1_hyst=5000 <-- Medium low fan speed
dtparam=poe_fan_temp2=80000,poe_fan_temp2_hyst=5000 <-- Medium high fan speed
dtparam=poe_fan_temp3=82000,poe_fan_temp3_hyst=2000 <-- High fan speed

Would that be the right way of interpreting it? If so, the first line I can change to poe_fan_temp0=20000 to have the fan always on at low speed and then set the second line to something like 55000 so that the fan kicks in at 55 degrees at medium low?

[TD540]

What's the highest maximum temperature for poe_fan_temp0 that is still safe enough ? My Pi seems to always stay below 80º which adjusts PoE-fan speed to 5000... but I wish it was off...

[anondrenched]

Hi!

Is there som new way to set the fan speed in 2021, on a PoE Hat?

Raspberry Pi 4, model b, rev 1.1
Kernel: 5.4.83-v7l+
Os: Raspbian 10 - Buster

Best regards