SuperMicro & low-RPM fans
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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.There are all of 3 fan settings in the BIOS, Full, Standard, and Optimal and I have the latest BIOS.
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.
Yes, I know. Leave it to Supermicro to presume everyone wants a screaming workstation.
Probably made for "their" tower/cooling options that are not exactly screaming ??
Why not see what they use in their tower?
Supermicro | Products | Chassis | Mid-Tower | SC732D4-903
Why not see what they use in their tower?
Supermicro | Products | Chassis | Mid-Tower | SC732D4-903
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.
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
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.
Correct.
I got the impression you were trying to lower the fan speed, not that it was ramping.
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.
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
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.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
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.
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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.
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?
You think they're a running closed loop PID control on the fans using the RPM feedback?
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.
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?
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?