SuperMicro & low-RPM fans

Discussion in 'Processors and Motherboards' started by altano, Nov 22, 2015.

  1. Stereodude

    Stereodude Active Member

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    That's what I figured.

    There are all of 3 fan settings in the BIOS, Full, Standard, and Optimal and I have the latest BIOS. :mad:
     
    #21
  2. T_Minus

    T_Minus Moderator

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    You get those + 1 more sometimes on IPMI boards so that's really not surprising.
     
    #22
  3. pLu

    pLu New Member

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    The BMC also has three fan profiles. What you're missing are fan thresholds (i.e. warnings) that kick the fans into full speed.
     
    #23
  4. Fritz

    Fritz Well-Known Member

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    Are these commands generic or do they need to be modified for each system (lanplus-H nas-sol??)??
     
    #24
  5. Stereodude

    Stereodude Active Member

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    So how am I supposed to fix this while keeping thermal based PWM control? Getting louder faster fans isn't what I consider a viable solution. They sell this thing as a workstation board. It's not a server board. Some level of tweaking should be offered. Compared to the customization level the average enthusiast type board offers it's a big joke. How hard would it have been to add a minimum RPM threshold in the BIOS?

    I have an idea on how to work around it, but it's going to be a giant pain and require programming a small microcontroller to basically multiply the RPM signals coming from the fans so the motherboard thinks they're spinning several times faster than they really are. :mad:

    Yes, I know. Leave it to Supermicro to presume everyone wants a screaming workstation.
     
    #25
  6. T_Minus

    T_Minus Moderator

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    #26
  7. pLu

    pLu New Member

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    Lowering a threshold doesn't lower fan RPM, the thresholds are for sensor warnings.

    The fan controller actually ignores the thresholds, which is why I have to lower them to not trigger the warnings.
     
    #27
  8. pLu

    pLu New Member

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    It's for configuring over the LAN (-I lanplus). You have to replace nas-sol with your own hostname or IP address.

    You can also run it as root on the server, which saves you some arguments:

    ipmitool sensor thresh FAN1 lower 300 300 400
    ipmitool sensor thresh FAN2 lower 300 300 400
    ipmitool sensor thresh FAN3 lower 200 200 300
     
    #28
    Fritz likes this.
  9. Stereodude

    Stereodude Active Member

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    Maybe I'm missing something, but my understanding is that the BIOS thinks the fans are running too slowly because they fall below some RPM threshold so it hits them with 100% duty until the RPM recovers. Then temperature control takes over again the RPM falls based on the PWM sent to the fan and the process repeats.

    It seems logical that the lower RPM threshold when the BIOS freaks out and ramps PWM duty to 100% should be adjustable in the BIOS. Alternatively, it should defeatable so that it doesn't care about the RPM the fan is spinning at.

    I'm not trying to slow the fans down. I never said I was.
     
    #29
  10. Fritz

    Fritz Well-Known Member

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    Thanks
     
    #30
  11. pLu

    pLu New Member

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    Correct.

    I got the impression you were trying to lower the fan speed, not that it was ramping.
     
    #31
  12. Stereodude

    Stereodude Active Member

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    Well, that certainly wasn't my intent.

    I guess I will start by complaining to Supermicro, though I don't expect them to do anything about it.

    I will need to get my scope and probe some signals so I can get a better idea on what I can do with a man in the middle attack on the tach signal coming back from the fans.
     
    #32
  13. Fritz

    Fritz Well-Known Member

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    What's a good Linux distro that runs from a USB stick and includes ipmitool?

    Thanks
     
    #33
  14. Stereodude

    Stereodude Active Member

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    I don't know if it's good, but this one has ipmitool. You can write it to a USB stick with Rufus.
     
    #34
  15. T_Minus

    T_Minus Moderator

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    Any idea why they say this?

    "Note the tips on suitable utilities to write the hybrid ISO image to bootable media; please do not use UNetbootin, Rufus, or UltraISO as those will cripple the result unfortunately."

    I normally throw in an Ubuntu SSD I use for misc stuff or Win7 for windows type stuff... I'm curious about the rescue linux w/tools already :D
     
    #35
  16. Stereodude

    Stereodude Active Member

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    No idea. I used Rufus and the USB stick booted just fine (using the ISO mode). Rufus also supports using DD for hybrid images, which seems to be what they want.

    Edit: Okay, it gave me the boot menu, but the ALT Linux option didn't work fully. Trying the DD written one now.

    Using rufus and selecting DD as the write method results in a working USB drive.
     
    #36
    Last edited: Mar 12, 2016
  17. Stereodude

    Stereodude Active Member

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    Okay, so I've ordered a few parts from Digikey (breadboard + level shifters) that will be used with a small 16-bit microcontroller board to frequency multiply the 12V tachometer signal coming back from the fans and outsmart the stupid Supermicro X9SRA board. The motherboard will think the fans are spinning 4x as fast as they really are and the fan pumping will be a thing of the past.
     
    #37
  18. T_Minus

    T_Minus Moderator

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    How will this affect the fans when the board needs to tell them to actually speed up if it thinks they're already running at high speed?
     
    #38
  19. Stereodude

    Stereodude Active Member

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    You think they're a running closed loop PID control on the fans using the RPM feedback? :confused: That couldn't possibly be the case unless they know the RPM vs. duty cycle characteristics for the exact fans your using...

    I'm would expect it doesn't care what the RPM is as long as it is above the minimum. Further, I expect that the PWM signal is driven by the thermal sensors for/in the CPU like a typical enthusiast board. As the CPU temperature rises it increases the PWM duty cycle to the fans. When the CPU temp drops it decreases the PWM duty cycle.
     
    #39
  20. T_Minus

    T_Minus Moderator

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    I don't know the electronic specifics of how the motherboard or fans communicate, etc... this is just a thought.

    You stated "The motherboard will think the fans are spinning 4x as fast as they really are"

    If the motherboard thinks the fans are already running fast then why would it try to increase the speed of them even if the temps went up which is what I figure makes the motherboard increase the fan speed anyway...

    Are you saying that the motherboard is simply going to continue increasing fan speed based on temp with no care of RPM / tricked RPM?
     
    #40
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