Hi All,
As with many people I have found one of the frustrating parts of working with the IPMI on Supermicro motherboards is that they don't play all that well with low RPM fans. I guess this is because in pizza box servers, all the fans are 80mm or smaller, and run at a high RPM as most of the components are passive beyond the cooling provided by the case.
With my Unraid home server this has been a been a bit of a pain in the bum, as the server is in 4u case, in a (silenced) "rack cabinet" (modified Ikea children's cupboard) and I really don't want everything running at full speed all the time.
There are some settings available in the IPMI (current motherboard is an X11SSH-F for reference, but I think this is fairly universal for Supermicro) which allow you to change between Standard, Full Speed, Optimal, Heavy I/O. None of these ever really got the results I wanted, and in most cases I found that the lower RPM of the bigger fans in my case trigger a "lower critical" event which set everything to full speed anyway.
I played around with the IPMI fan speed tool in Unraid (I think this is available in other OSes too) and managed to get some results, but it seems there is still only 2 "zones" that I can control. One of them is numbered fans (FAN1234) and the other is FANA.
Whilst I did manage to drop the speeds a bit, I was still limited by the "lower critical" trigger on the lower RPM fans meaning even when all drives are off and my CPU is idling, I'm still running at over 50% speed to prevent the IPMI overriding any custom control with "Full Speed".
Today, whilst pondering this conundrum, I had an idea, and it isn't revolutionary by any stretch of the imagination, but I realised that if I actually just split one of the fan headers out (note: I made a point of using one that provides 12v power separately so I don't overload the header) then the motherboard only gets the sensor reading of a single fan.
The fans on the back of my case are 2200RPM 80mm Arctic CO fans... so they can provide sensor information, but will allow me to send a lower PWM signal to the other ones.
The CPU can go onto FANA so that it is it's own "zone" and spin up and down completely separately. That also revs up pretty high at max, like 3000 RPM. I wasn't too worried about this one as it's lowest value doesn't trigger "lower critical".
Here are the values I settled on in the Unraid IPMI tool:
15% based on hard drive temp is pretty darn good. The 80mm fans are running at 800rpm, but the big 140mm fans on the front of the case, and the 92mm blowing across the PCH and NVME drives are now completely tamed. I might move the PCH one over to the FANA header but honestly that gets enough residual air flow from the CPU cooler.
For anyone else who wants to find the limits of their set up, the way I did it was open IPMI and the Controller tool next to each other:
Make sure you enable "auto refresh in IPMI, set the minimum temp to the same as the maximum, so it never triggers during the process, then experiment with the minimum speed either going from the bottom up or top down, one option at a time until you no longer trigger (or trigger) the "lower critical". You can keep an eye on IPMI to see the RPM that the PWM % will result in.
If you trigger the critical alarm and everythign goes full speed, it's no big deal, it will attempt to override it when you send a new command, assuming that doesn't also trigger it. You might need to force both "zones" to recalculate separately.
Remember to set your minimum temp back to something sensible after you have finished.
Additional Word of warning: Having you fans on the headers means the IPMI can monitor it, and set them all to full if one of them fails. This obviously prevents this from happening.
I know this isnt genius level stuff, but figured there might be a couple of people out there in the same boat as me who haven't figured anything out yet.
As with many people I have found one of the frustrating parts of working with the IPMI on Supermicro motherboards is that they don't play all that well with low RPM fans. I guess this is because in pizza box servers, all the fans are 80mm or smaller, and run at a high RPM as most of the components are passive beyond the cooling provided by the case.
With my Unraid home server this has been a been a bit of a pain in the bum, as the server is in 4u case, in a (silenced) "rack cabinet" (modified Ikea children's cupboard) and I really don't want everything running at full speed all the time.
There are some settings available in the IPMI (current motherboard is an X11SSH-F for reference, but I think this is fairly universal for Supermicro) which allow you to change between Standard, Full Speed, Optimal, Heavy I/O. None of these ever really got the results I wanted, and in most cases I found that the lower RPM of the bigger fans in my case trigger a "lower critical" event which set everything to full speed anyway.
I played around with the IPMI fan speed tool in Unraid (I think this is available in other OSes too) and managed to get some results, but it seems there is still only 2 "zones" that I can control. One of them is numbered fans (FAN1234) and the other is FANA.
Whilst I did manage to drop the speeds a bit, I was still limited by the "lower critical" trigger on the lower RPM fans meaning even when all drives are off and my CPU is idling, I'm still running at over 50% speed to prevent the IPMI overriding any custom control with "Full Speed".
Today, whilst pondering this conundrum, I had an idea, and it isn't revolutionary by any stretch of the imagination, but I realised that if I actually just split one of the fan headers out (note: I made a point of using one that provides 12v power separately so I don't overload the header) then the motherboard only gets the sensor reading of a single fan.
The fans on the back of my case are 2200RPM 80mm Arctic CO fans... so they can provide sensor information, but will allow me to send a lower PWM signal to the other ones.
The CPU can go onto FANA so that it is it's own "zone" and spin up and down completely separately. That also revs up pretty high at max, like 3000 RPM. I wasn't too worried about this one as it's lowest value doesn't trigger "lower critical".
Here are the values I settled on in the Unraid IPMI tool:
15% based on hard drive temp is pretty darn good. The 80mm fans are running at 800rpm, but the big 140mm fans on the front of the case, and the 92mm blowing across the PCH and NVME drives are now completely tamed. I might move the PCH one over to the FANA header but honestly that gets enough residual air flow from the CPU cooler.
For anyone else who wants to find the limits of their set up, the way I did it was open IPMI and the Controller tool next to each other:
Make sure you enable "auto refresh in IPMI, set the minimum temp to the same as the maximum, so it never triggers during the process, then experiment with the minimum speed either going from the bottom up or top down, one option at a time until you no longer trigger (or trigger) the "lower critical". You can keep an eye on IPMI to see the RPM that the PWM % will result in.
If you trigger the critical alarm and everythign goes full speed, it's no big deal, it will attempt to override it when you send a new command, assuming that doesn't also trigger it. You might need to force both "zones" to recalculate separately.
Remember to set your minimum temp back to something sensible after you have finished.
Additional Word of warning: Having you fans on the headers means the IPMI can monitor it, and set them all to full if one of them fails. This obviously prevents this from happening.
I know this isnt genius level stuff, but figured there might be a couple of people out there in the same boat as me who haven't figured anything out yet.
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