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Faking the fan signal


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 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. 


This is for the HP Microserver Gen8 only.

I'm pretty sure that your 350 has another type of fan connector(s) and probably a different kind of protection.


You can PM me with additional info since I'm not checking this topic nor getting new post notifications for it.

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  • 2 weeks later...

Update: Due to the extremely helpful guidance from MihaiT in private conversations I was able to fake the fan signals of all four fans of my Proliant ML350p v2. With 2 CPUs HP forces you to buy a fourth fan, you can't use just the three it comes with for 1 CPU, and although they're honestly not too loud at low CPU usage and with the plastic shroud and cover back on, you can still hear them, and I wanted to turn them off, all four of them. I let it run for a while and noticed that nothing gets hot even at high CPU usage for the entire system except for the heatsink over the SmartArray controller. But I asked an HP systems expert, he told me it's normal that those SmartArray heatsinks get hot.


What's so nonsensical about this is the fact that HP enforces the number of system fans, but not any cooling for the CPUs. They want you to use heatsinks on the CPUs, but that is not enforced/measured in any way. In other words, if you use three instead of four system fans, the system triggers an alarm and shuts down (silly, in general), but if you don't use any cooling at all on the CPUs, even at super-high loads, it doesn't care (silly as well). Makes no sense to me.


I bought two Enermax ETS-T40-TB CPU Coolers because I found that they have received outstanding reviews, including near-zero noise even at full speed. I didn't care about the fact that they are so tall that I can't put the cover back on the server (it's a rack-mount, not a tower, so the motherboard lies horizontal), because I wanted to remove the four fans anyway, and at near-zero noise I might as well leave the cover open. I also didn't care about the fact that I couldn't speed-control the Enermax, because they are so quiet even at full speed. All you hear is a bit of a "whoosh". So now I have the two Enermax CPU coolers protruding and can't put the cover back on, but I have much better cooling than what HP wants you to do (unenforced heatsinks), and I have much lower noise than if I had left the four system fans in that HP would have required me to use. Four fans required at low load, but no heatsink enforced at high loads? Give me a break.


So in the ML350p v2 you do this: you short the two black pins and the one yellow pin, that's it. You've successfully faked the presence of a cooling fan. And then you can do that will all 3 or 4 that you were supposed to use. Incidentally, that left the red pin unused, and you simply connect the red pin of the Enermax to the red pin of the fan connector, and you connect the black pin of the enermax to ground. You leave the other two of the Enermax unused (yellow and blue, and that means full rpm and no speed control on the Enermax, but as they're so quiet I'm cool with that, pun intended), and you leave the green pin of the system fan connector unused.


I also found a way to connect those Enermax directly to the motherboard with the brackets and mounts that they ship with. They are actually *incompatible* with the motherboard of the ML350p v2. For Intel CPUs, their mounting kit has you remove the motherboard, put mounting stubs on the underside, then put more brackets and clips and other parts on the upper side, etc. But on the ML350p v2 motherboard, there are no holes for that, because this motherboard comes with brackets and an assembly for the heatsinks. But I found a way to use some of the parts from the Enermax kit and the brackets already on the motherboard to press the contacts of the cooling blocks directly onto the CPUs. Contact me if you need details, it's a bit complicated to describe. You can make it work so that it fits snug and gently presses on the CPU without any additional tools or parts, simply by abusing parts of the mounting kit with the brackets already on the motherboard in a way that was not intended. I thought I might need to use some aviation safety wire for a guaranateed custom mounting, but with some experimentation I found a way to do it without metal wiring, just abusing what I already had.


Thanks MihaiT for your guidance on the system fans!


I now have the quietest and best-cooled system I could think of (I won't need liquid cooling). My only extra cost was the two Enermax, but I think their price is decent, and I could now even sell those four fans on ebay. One of those system fans is pricier on ebay than one of those two Enermax. If I do that, my net result would even be a net gain. I also save on electricity, because every fan sucks up to 4.5A, and every Enermax sucks up to 0.45A, that's precisely 1/10. So now I have 0.9A max vs. 18A max.


Disclaimer: use at your own risk, I assume no liability. Of course, you can still mess this up and destroy your hardware!


If there's any way to make the SmartArray heatsink cooler, I'd appreciate a message. I only use one drive, no RAID.

Edited by Cainoom
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  • 4 months later...

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?


Hi i was interested in the question raised by tedaz as i have been having a similar probelm getting my Gen 8 to recognise a Coolink Swif2 120P 4pin PWM fan using your option 3 method

But i realise that i dont think my fan has rotation detect and thats why its not working and the server is reporting an incompatable fan


If i wire it up using method 2

Connect pins 4,5,6 together in order to fake the fan presence.

Connect new fan's:

- +12V wire to pin 1

- GND  wire to pin 5/6

- PWM wire to pin 3


Then it works but the fan is running at 100% speed and is noisy


So is there a way to get a PWM fan without rotation detect to still be controlled by the MB?

Also im struggling to find a fan that has rotation detect, could you reccomend one from here:



last question if i put a resistor inline to lower the 12v will that lower the speed of the fan?

how about using one of those 3 pin variable speed controls with a 3pin RPM fan? would that work


Ideally id like to achieve just fooling the Gen8 with a lower quieter 4pin RPM fan but that seems to be getting almost impossible

can anyone reccomend a really low rpm fan that has the rotation detect?i will hardly be stressing my server at all and im looking for as close to silent as i can get

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  • 3 weeks later...

Hi there


can some tell me the type/name/ordernumber for the casefan connector ?


Any idea where in Austria / Germany i can get this connector ?







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  • 5 months later...

First of all I want to thank MihaiT for his work. I found it in a Microserver review on SPCR(http://www.silentpcreview.com/article1377-page1.html).


The connector

Because it was not clear how to find a proper connector I've done some research.

I found that HP use this type of 6-Pin Connector for fans of the DL360 and DL365 series.

Luckily I was able to find one of these cooling systems in an old DL360 G5 server in my company which wasn't disposed yet.

So I can confirm that the connector has the same dimensions, but without the secure brackets left and right.

Here is the HP Spare Part Number for a DL360 G5 fan: 412212-001

You can get one of these fans for about 4€, may its a bit expensive to just use the connector for an adapter cable but its reasonable enough I think.

May there are other Spare Parts for G6/G7/G8 that you can buy renewed or defective at ebay.


But I guess you can also use two "3-Pin JST" connectors or two "4-Pin MPC"(Also know as cd audio connector) and just cut off the unnecessary plastic.


I think you just cannot buy this hp proprietary 6-Pin Fan connector. I also found no fan from suppliers like Inventec with this connector. It seems that this connector is only used in HP server hardware.



The next thing is about these Rotation Detect / Locked Rotor Sensor.

Like MihaiT already said it is not recommendable to connect the RPM Signal from an ordinary PWM fan to the Rotation Detect Pin (PIN 4).

My choice is to use method 3 of short circuit Pins 4,5 and 6 and connect them to ground of the 4-Pin connector and use Pin 1 and 3 for voltage and pwm control and leave the rpm signal from fan unconnected. I use the mentioned 6-Pin connector from an old hp fan to solder an adapter to connect any 4-Pin fan.


The fan

The original fan from delta systems has a maximum airflow of 112CFM / 191 m³/h rated at 46,5dB from delta.

(Because I cannot determine the exact model, I can only assume that it is a AFB1212SH-R00 or some predecessor) 

Product sheet: http://www.delta.com.tw/product/cp/dcfans/download/pdf/AFB/AFB120x120x25.4mm.pdf



If the problem with "method 3" that snakemetal mentioned above (100% fan speed) is true for most of the fans, the safety way is to use some silent 15-20dB PWM fan with an airflow of around 60CFM / 102 m³/h or more and use method 2 "no fan attached" and connect the fan to the psu with a 4-Pin Molex fan adapter. In this case you don't even need to build some 6-Pin connector, just use one of the 3-Pin JST to short circuit the pins.

(For example the enermax T.B. silence PWM http://www.enermax.de/luefter/tbsilence-pwm/)

EDIT: But maybe the problem it's just a result of the 3,3/5 V PWM Signal story, unfortunately most fan manufacturers doesn't tell if their fan need 3,3 or 5V for the PWM signal. But the common version seems to be the 5 volt variant. /EDIT

Even quieter fans(8-14dB) doesn't make sense because of the noise from PSU fan(don't know exactly how many dB) and hard drives(dB value depends on hard drive model).

The enermax T.B. silence is rated at 18 dB while providing 71 CFM airflow. 3,9 CFM per dB, so nearly two times more noise efficient than the original delta fan(2,4 CFM per dB). 


For systems with G1610T and G2020T there's no reason to fear overheating because the original fan runs at only 6-15% according to iLo even with high cpu load and high transfer rates at local storage over hours.(own measurements at 19-25°C room temperature)

Any good silent fan(1000-1500rpm) at 100% fan speed is quieter than the built in delta fan on slow speeds which is about 29dB and the fan at full speed probably provides more air flow than the slow spinning delta fan. (http://www.silentpcreview.com/article1377-page6.html)


May you ask yourself how to find fans with this rotation detect / locked rotor sensor signal.

In my opinion this is one option you should not consider, because nearly all ordinary fans you can buy like Enermax, Bequiet, CoolerMaster etc just use the tachometer type, because its more common for "normal" PCs like office, gaming and HTPC. 

These RD type fans are mostly produced by suppliers like delta, sunon or mechatronics (http://www.coolerguys.com/lras.html). These fans are designed for industrial environments like production lines, therefore they don't have to be quiet, they are designed to be solid, fail safe and to deliver a continuous air flow.

The most silent ones still emits > 35 dB noise.

Edited by Bloodsaw
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  • 6 months later...
Some time ago I wrote to Noctua support with question connected to PWM voltage of NF-S12A. The answer following:


"As far as I can tell the NF-S12A-pwm should work just fine with 3,3v pwm signal."


I bought and install NF-S12A to my MS G8. I was afraid that it will not work, but faced a very different challenge. 


Firstly PMW signal from iLo never exceed 70% and fan is not enough power to blow the whole body (CFM 63 vs. 113 original). Given the fact that the room temperature is about 27-28 degrees, the temperature inside the housing 31-32 degrees. Fan is running at top speed. But it's still quieter than the original. 


I can't you server for heavy tasks. After 30 min under cpu miner test the temp on sys exhaust and PCI zone going to 95% of max value. 

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Hi guys.

First of all, awesome write up on the fan modding, haven't found much else like this anywhere.


I recently got my hands on a DL380p Gen8 which i want to mod, and after i read this thread i'm convinced the fan connector has the same layout.

I want to basic with some fans connected which will run at 100%, so no PWM.

So how should i connect the fans? I would need pin 1 (+12V) and next i would a ground which could be either pin 5 or 6 i assume, but when i look at the diagrams, pin 4-5-6 are tied together or connected to the fan, what should i do in my case, still tie together pin 4-5-6 and also connect the ground from my new fan?


Thanks in advance guys, very nice guide :-D


BTW. Is there a forum thread or something else where i can see some DL/ML server hacks/mods? pictures and guides are more than welcome.

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Hmm, just tried to remove an extra LSI controller in one of the expansion slots.

This resulted in all OEM fans running at 6% even during 30 minutes of 50% stress load on all cores and without any signifikant rise temps, so i'm gonna test a little with the standard fans for now. 

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  • 4 weeks later...

If the problem with "method 3" that snakemetal mentioned above (100% fan speed) is true for most of the fans, the safety way is to use some silent 15-20dB PWM fan with an airflow of around 60CFM / 102 m³/h or more and use method 2 "no fan attached" and connect the fan to the psu with a 4-Pin Molex fan adapter. In this case you don't even need to build some 6-Pin connector, just use one of the 3-Pin JST to short circuit the pins.

(For example the enermax T.B. silence PWM http://www.enermax.de/luefter/tbsilence-pwm/)



I am interested in trying this method, its summer in AZ and my microserver is getting loud! What is this 3-Pin JST and how does it connect to the fan header? I have some pretty quiet high performance 120mm fans I could use.

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