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Faking the fan signal


MihaiT
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I was running iLo 1.40 and downgraded to the unofficial 1.32 without problems, FWIW.

 

That's very tempting as I'm running Ubuntu and ZFS so use my main 4 drive slots in AHCI mode on one of my Gen8 MicroServers...

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  • 1 month later...

Does this mod will still keep the PWM speed control?

Motherboard FAN connector pinout :

 

attachicon.giffan.png

(right click, open in new tab)

 

 

No FAN attached :

 

attachicon.gifnofan.png

(right click, open in new tab)

 

Attach a more silent FAN with rotation detect/ locked rotor signal :

 

attachicon.gifrdfan.png

(right click, open in new tab)

 

Personally I'd go replacing the FAN with a silent one which has ~ 75% of the original fan's airflow. I don't use the server for heavy tasks and I think it will be enough. 

 

Whatever you do, pay attention and leave the thermal protection enabled in the BIOS. If you have add-on cards or high env. temp., try to install some smaller fans inside.

 

The original disclaimer still applies. 

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Yes, but remember, you'll need a 3.3V PWM fan. 

Sorry for I'm a little confused - normal PWM fans are 12V, could you give a specific brand and model of 3.3V PWM fan?

 

For the HP fan, pin4 is the Rotation Detect, I can understand short circuit 4-5-6 to "cheat" the mainboard, but why connect HP pin4 to PWM pin3 (pwm sense pin) wouldn't trigger error message?

 

I'm planning to purchase a Noctua NF-S12A PWM fan, its pins defined as this: 1 GND, 2 +12V, 3 Sense, 4 PWM.

Does this fan will work ok follow your "rdfan.png"?

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Sorry for I'm a little confused - normal PWM fans are 12V, could you give a specific brand and model of 3.3V PWM fan?

 

For the HP fan, pin4 is the Rotation Detect, I can understand short circuit 4-5-6 to "cheat" the mainboard, but why connect HP pin4 to PWM pin3 (pwm sense pin) wouldn't trigger error message?

 

I'm planning to purchase a Noctua NF-S12A PWM fan, its pins defined as this: 1 GND, 2 +12V, 3 Sense, 4 PWM.

Does this fan will work ok follow your "rdfan.png"?

 

I was referring to the PWM signal level which can be 5 or 3.3 volts. The motherboard didn't supplied more than 3.3V during my tests. 

 

~Mihai

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I was referring to the PWM signal level which can be 5 or 3.3 volts. The motherboard didn't supplied more than 3.3V during my tests. 

 

~Mihai

Thanks for your reply.

It should be ok, if the motherboard only output 3.3V for a 5V fan, the highest speed will be a little lower than the fan's design.

 

Connect HP pin4 to PWM pin3 (pwm sense pin) wouldn't trigger error message? Except the 3.3V/5V problem, is it ok to use a Noctua NF-S12A PWM fan follow your "rdfan.png" (without any iLO error message)?

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Thanks for your reply.

It should be ok, if the motherboard only output 3.3V for a 5V fan, the highest speed will be a little lower than the fan's design.

 

Connect HP pin4 to PWM pin3 (pwm sense pin) wouldn't trigger error message? Except the 3.3V/5V problem, is it ok to use a Noctua NF-S12A PWM fan follow your "rdfan.png" (without any iLO error message)?

 

1.) "rdfan.png" is for a fan that has rotation detect output, which your noctua doesn't have. In order to make it work, simply short the yellow wire to both grounds, and leave noctua's rpm output pin unconnected. 

 

2.) Most of the fans need a minimum voltage level on the PWM rail to start and maintain speed. Putting a 5V PWM controlled fan on the 3.3V motherboard could lead to a stopped fan when driven to minimum...   Your server, your choice !

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1.) "rdfan.png" is for a fan that has rotation detect output, which your noctua doesn't have. In order to make it work, simply short the yellow wire to both grounds, and leave noctua's rpm output pin unconnected. 

 

2.) Most of the fans need a minimum voltage level on the PWM rail to start and maintain speed. Putting a 5V PWM controlled fan on the 3.3V motherboard could lead to a stopped fan when driven to minimum...   Your server, your choice !

Thanks, this means with the noctua fan, only connect HP pin1 and pin 3 to the fan, short pin 4-5-6 and connect them to noctua's ground, right?

And this still enable the fan received the PWM signal from the motherboard?

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  • 5 months later...

MihaiT, I don't find that 6pin connector on the motherboard. Perhaps this is only on microservers (as that is the name of this discussion group)? I have a Proliant 350p v2 Gen 8, p/n 652063-B21. If there is any way to fake the fan signal on this motherboard, I'd like to know. I have exactly those fans you are referring to (have found the same instructions for the PFR0912XHE from Delta Electronics), but for my life of it, I just don't have that 6pin connector on my motherboard. Any help from anyone great appreciated! I'd like turn off 2 of those 4 fans and use two PWM fans instead (and directly on the two CPUs, instead of just using heatsinks). Thanks!

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