SuperMicro & low-RPM fans

altano

Active Member
Sep 3, 2011
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Cambridge, MA
Hey Everyone,

So the internet is littered with people discussing the problem where SuperMicro boards will oscillate between running your fans at "full" and "optimal." The issue is that low-RPM fans trigger an alert and cause the board to go into FULL fan mode until it realizes temps are okay, and then it goes back to normal, which slows the fans below the limit again, over and over.

I've read all the guides about using ipmitool to lower the sensor thresholds and I was able to do this (I recommend booting to PLD Linux Rescue Live CD over IPMI, which is tiny and comes with ipmitool) but that didn't seem to help. I was still seeing fan assertions in the event log and the speed oscillation. I then lowered the threshold all the way to 0 (for all 3 thresholds) and I'm still getting the issue.

Has anyone successfully fixed their SuperMicro board to work with low-RPM fans, and if so, did you have to do anything else?
 

FMA1394

Active Member
Jan 11, 2013
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If these are PWM fans, just get a PWM controller and hide it somewhere. Using resistors is the wrong way to go.
 
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altano

Active Member
Sep 3, 2011
164
47
28
Cambridge, MA
The problem with a resistor is that the fan can then only spin at one speed (full - whatever the resistance is). Right?

As for a PWM controller (yes these are PWM fans), can you be more specific? What would control the speed if not the motherboard?
 

FMA1394

Active Member
Jan 11, 2013
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A knob.
Something like this. You'll have to make the solution yourself. ZALMAN FAN MATE 2 Controller, Panel - Newegg.com

Like this,
Suppose you have a 4pin fan. Ground, Hot, Speed Sense, PWM.
What you need to do (for each fan) is have the ground, hot, speed sense going into the motherboard. split the ground off and have that go into a 4 pin connector with the PWM wire and hook that into the pwm controller. So,
1. the power and speed sensing are provided/given to the motherboard
2. the ground and pwm signal are provided by the zalman.

By doing it like this, you don't burn up the PWM controller and create fire hazards AND you don't have to buy a fan controller for each fan.

Get creative, and good luck.
 

britinpdx

Active Member
Feb 8, 2013
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Portland OR
Are changes made by using the ipmitool persistent ? I seem to remember from tinkering in the past that they weren't and a power cycle (or cold reboot of the BMC) lost the changes.

What's your use case ? I presume you are looking for a quiet system ?

I've always referred to the Supermicro Fan Matrix for guidance when it comes to choosing a specific fan size for a specific use case.
 

wbo

New Member
Aug 4, 2015
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Another option (although a bit more expensive) is to use a fan controller that is capable of handling high-wattage fans, such as the Aquaero 6 which has 4 PWM channels that can handle up to 30W each. The version I put in my SC846 is at http://shop.aquacomputer.de/product_info.php?products_id=3092

I put the front 3 fans each on their own channel and put the rear fans together on the 4th channel. The LCD panel is removable, so I took it off and mounted the fan controller inside the case and connected it to an internal USB header.

The software included with the controller lets me set a custom fan curve for each channel based on temperatures from the thermal probes connected to the Aquero or based on temperatures reported by hard drives and the CPU. It is a bit expensive but very customizable and with it, the case is nearly silent when idling with SQ PSUs installed.
 

fagiano

Member
Feb 5, 2011
43
7
8
Singapore
A quick and dirty solution is to disconnect the PWM wire, the fan will spin at full speed then use a "low noise adapter"(aka a resistor) to slow down the fan to a reasonable speed. You loose speed control, I personally can live with that.

OT: I've been thinking to build a gizmo that multiplies the tachometer signal to fool the motherboard when using slow fans (but retaining speed control), It would require just a 2$ or 3$ worth of components... as soon as I have some spare time :D .

Alberto
 

Marsh

Moderator
May 12, 2013
2,284
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@fagiano
There is a easier way for the quick and dirty solution
Get one of this cable
Gelid 1-to-4 Splitter CA-PWM-03 PWM (4Pin Molex/4Pin PWM to 4 x PWM Header)

Re-pin the molex power cable from 12v to 5v. Plug in pwm sensor wire to the systemboard.
All 4 fans are running at 5v, even at full speed, much quieter and descent airflow.

I have many chassis, this is the cheapest way to accomplish the quick and dirty method.
Do not use resistor, the systemboard would just ramp up the fan , causing the resistor to overheat.
 
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PigLover

Moderator
Jan 26, 2011
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@fagiano
There is a easier way for the quick and dirty solution
Get one of this cable
Gelid 1-to-4 Splitter CA-PWM-03 PWM (4Pin Molex/4Pin PWM to 4 x PWM Header)

Re-pin the molex power cable from 12v to 5v. Plug in pwm sensor wire to the systemboard.
All 4 fans are running at 5v, even at full speed, much quieter and descent airflow.

I have many chassis, this is the cheapest way to accomplish the quick and dirty method.
Do not use resistor, the systemboard would just ramp up the fan , causing the resistor to overheat.
I've had trouble with SM fans not starting on 5v. Even 7v is spotty (running them between the 12v and 5v line on the Molex). YMMV.

Also - be cautious with resistor cables. Most of them are built for consumer fans that draw <1w run running full speed. SM fans can run 20-30w and will burn up the small resisters used on most of these cables.
 

Lost-Benji

Member
Jan 21, 2013
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The arse end of the planet
The "hack" way to do this is to use an in-line resistor on a higher-speed fan. I have had to use these in the past: http://www.amazon.com/gp/product/B0...e=as2&tag=servecom-20&linkId=4E6XUGIV4DDJKID3

This is an issue I have brought up to some of their PMs/ support folks.
NOOOOOOOOOO, PWM fans need full 12V rail all the time, the forth pin sends the pulse width to the controller in the fan motor to set speed/power of fan.

A pulse doubler is the correct way to tell system that fan is turning twice as fast. Not easy to find or implement.

Easier to get better fans and set the BIOS fan profiles.
 
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Marsh

Moderator
May 12, 2013
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I waited until fagaino looking for a quick and dirty solution, running fan at 5volt is not ideal or proper solution.
It only cost $10 bucks ( $6 each when buying 10 pieces, I brought 10 pieces), worth a shot.

I used the above cable in Supermicro chassis with 4 pin fans. It keeps 16 drives running cool.

I have few chassis, $50 for fan controller per chassis adds $$ up quick.
 

pLu

New Member
Nov 25, 2015
19
4
3
Stockholm, Sweden
I've built a Supermicro Avoton NAS with two Noctua NF-A9 PWM and one Noctua NF-A14 PWM. Also had the fan problem but configured the RPM thresholds according to the fan specs like this:

ipmitool -I lanplus -H nas-sol -U ADMIN -P ADMIN sensor thresh FAN1 lower 300 300 400
ipmitool -I lanplus -H nas-sol -U ADMIN -P ADMIN sensor thresh FAN2 lower 300 300 400
ipmitool -I lanplus -H nas-sol -U ADMIN -P ADMIN sensor thresh FAN3 lower 200 200 300

Problem solved.
 
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pLu

New Member
Nov 25, 2015
19
4
3
Stockholm, Sweden
Are changes made by using the ipmitool persistent ? I seem to remember from tinkering in the past that they weren't and a power cycle (or cold reboot of the BMC) lost the changes.
The changes are persistent, like all other settings like network and users. I guess there's a risk losing them when upgrading the IPMI firmware.
 

TType85

Active Member
Dec 22, 2014
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Garden Grove, CA
I've built a Supermicro Avoton NAS with two Noctua NF-A9 PWM and one Noctua NF-A14 PWM. Also had the fan problem but configured the RPM thresholds according to the fan specs like this:

ipmitool -I lanplus -H nas-sol -U ADMIN -P ADMIN sensor thresh FAN1 lower 300 300 400
ipmitool -I lanplus -H nas-sol -U ADMIN -P ADMIN sensor thresh FAN2 lower 300 300 400
ipmitool -I lanplus -H nas-sol -U ADMIN -P ADMIN sensor thresh FAN3 lower 200 200 300

Problem solved.
Thanks for this. It fixed my problems I had getting my Norco 4220 to be quiet.

I put in the Noctua PWM 120mm industrial fans in the middle, 2 Noctua PWM 80mm in the back along with Noctua HSF's to cool a pair of 2620's. The fans would ramp when the board saw them to low. Now it's nice and quiet and my wife can't complain :)
 

Stereodude

Active Member
Feb 21, 2016
412
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USA
I've built a Supermicro Avoton NAS with two Noctua NF-A9 PWM and one Noctua NF-A14 PWM. Also had the fan problem but configured the RPM thresholds according to the fan specs like this:

ipmitool -I lanplus -H nas-sol -U ADMIN -P ADMIN sensor thresh FAN1 lower 300 300 400
ipmitool -I lanplus -H nas-sol -U ADMIN -P ADMIN sensor thresh FAN2 lower 300 300 400
ipmitool -I lanplus -H nas-sol -U ADMIN -P ADMIN sensor thresh FAN3 lower 200 200 300

Problem solved.
Will this work on my Supermicro X9SRA? It doesn't have a BMC. I haven't gotten an OS installed on the system yet (still testing RAM and other stuff), so I can't try it. My fans are all 140mm (CPU fan included) and don't need to spin fast.
 
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