Supermicro 846 TQ backplane PWM headers question ....

[moxford]

I see the the TQ has 4 4-pin fan headers.

However, I don't see a data-cable connecting the backplane to the mobo, just power connectors.

Who/what controls the PWM functionality? Are there onboard-temp sensors? Am I missing a cable?

Thanks!

-mox

 

[i386]

I think @T_Minus posted that you need an i2c cable from your backplane to mainboard to control them.

 

[PigLover]

Correct. There is an i2c connector on the backplane that you connect back to a SM motherboard that has a backplane i2c connector. Not all of the SM motherboards have them - but if they do and you make the connection then the various sensors on the backplane (power and temp) will be visible in the IPMI sensor data (the SPD table) and the fans will be under the control of the BMC on the motherboard.

Without this connection any fan plugged in to the MB fan headers will spin at full speed (100% pwm duty cycle).

You can also plug in the i2c cable if you are using the chassis as a JBOD housing and use the CSE-PTJBOD-CB3 power board and get sensor data and fan control from the IPMI on the power board.

 

[moxford]

Motherboard only has a single "PWRI2C" header and the TQ docs don't say anything about PWM. Wonder if those fans can actually be controlled if I were to put an I2C splitter on it.

 

[K D]

I just posted this question in a separate thread.

Where do I find an i2c splitter?


Sent from my iPhone using Tapatalk

 

[moxford]

I found some smaller i2c pcb ones for drones, but nothing off the shelf that seems to fit the headers. It's a broadcast/bus so we should be able to just put each of the headers in parallel, solder them, and heat-shrink for insulation. Basically a 6-1 harness. Should be pretty trivial ... hardest part is finding the right connectors. I *THINK* that the CBL-CDAT-0601 is the right part for the SMBus header, so I might order a few and just start splicing.

Might be possible to custom daisy-chain them as well, which would be cleaner, but a bit more work.

Let me know if you find an actual splitter ....

-mox

 

[1obro]

This thread might be old but I have a similar problem. I have a 836 chassi from Supermicro with a SAS836-TQ backplane. However, i have a motherboard from Gigabyte.
I want to be able to utilize the fan headers on the backplane but i fear that i can't control the PWM signal with my motherboard.
If i connect fans to the backplane, they run at full speed.

My motherboard is a GA-7PESH2. It has a SGPIO connector and I use the SGPIO side band cable to get HDD acivity from the backplane and that works like expected.

There isn't a i2c connector on my board but there is something that the manual refers to as "ipmb" connector. Can't figure out what that connector is for though.

Any input?

 

[MisterE]

Warning to the community. I was also testing a i2c cable between X11SCL-F and a BPN-SAS2-846EL1 backplane. Wanted to try to control the fans and/or get extra statistics (temperature). Created a TrueNAS forum thread.

PigLovers post is stating that this works. This seems not generally true. Maybe it worked for him but this is not possible with my hardware according SuperMicro.