HP z840 cpu/memory fan connector pinout

[andrey2345]

Hello,

I am hacking HP z840 motherboard to work outside original chassis. And I am looking for help to figure out cpu/memory fan connector pinout. The one marked in red:

link to image https://ibb.co/TggMtjJ

[DGroves · Accepted solution]

pinning out the fan header is a very basic thing it only requires a multimeter or a continuity tester

simply connect one lead to a motherboard ground and test all of the pins one by one, those that show a reading are ground

now do the same for the +12 

the ones that are left are the sense pins

you can also do this from the cooling shroud, if you look at the area where it mates to the motherboard header you will see the wires where each fans 3 pin connector is attached to the main pin header array

again a simple pinout will reveal the wiring of which pin connects to the main header

note also that the fan 3 pin connector follows the standard fan pinouts of ATX motherboard fan headers

you can also buy a premade wiring harness that adaptecs the motherboard to a standard ATX supply on ebay or aliexpress/alibaba

http://h10032.www1.hp.com/ctg/Manual/c04823811.pdf

[andrey2345]

Thanks a lot. I already got the ATX adapter wires and connected CPU  fans to AUX 3 pin fan connectors. But I get POST errors and fans run at full RPM. So I was thinking I need to figure out a way to connect them to the main cpu/memory header. I was just hoping someone already went this way.

[DGroves]

the case/memory fans are going to run at full speed until you connect the "ambient air Temp" sensor

this sensor lives in the power cable, and is a simple transistor that connects to the motherboard, please see the service manual for the proper pins it connects to. i have posted on this forum several times on this subject do a "forum "search" for

z820 all fans spin at full speed ambient air temp

[andrey2345]

Thanks again! I've found the thread. I don't have original HP chassis, so I am not sure which temp sensor I need. Will have to experiment. I am guessing I'll start with some standard 10k or 100k NTC 

[andrey2345]

Is there anything I can do about POST errors on boot? I searched the forum but was unable to find solution that would work for me

[DGroves]

no, the ambient temperature sensor is a common transistor, however i strongly recommend you do not reinvent the wheel so to speak, simply BUY THE Z820/Z840 POWER CABLE as it will provide you with a power on light a system error light a Speaker, a Ambient temp sensor (search ebay for best price)

https://www.ebay.com/itm/Genuine-HP-Z820-Cable-Assembly-Power-Switch-Speaker-644320-002-644320-001/1...

https://h30434.www3.hp.com/t5/Business-PCs-Workstations-and-Point-of-Sale-Systems/Thermal-Sensor-not...

you will also need the front USB/Audio Panel

https://www.ebay.com/itm/HP-Hewlett-Packard-Z820-Desktop-Front-USB-I-O-Assembly-with-Cable-671715-00...

 a ATX to motherboard power adapter

https://www.ebay.com/itm/1PCS-HP-Z840-ATX-power-supply-line-24P-to-18p-CPU-8pin-adapter-TGC-1568-A1/...

and the z840 power supply chassis wiring harness, and the motherboard memory power harness

in my opinion not a worthwhile conversion as you get a suboptimal power supply, a suboptimal case  with poor cooling.

the HP z840 motherboard vrm and other components must be actively cooled or the board will fail

HP barebones case, needs power supply and Drive brackets 300 dollars

https://www.ebay.com/itm/HP-Z840-WORKSTATION-BARE-CASE-CHASSIS-731917-006/303562329281?hash=item46ad...

my opinion,.....................buy the z840 

[andrey2345]

Thank you for so much useful information! Really appreciate the effort! HP has great community. And I totally agree with you that I should just buy the z840. But...

1. I leave on the other side of the globe, and we do not have e-bay here ;(

2. I could find a used z840 in here, but the price tag would be around 1500$.

3. I've already invested in all the major components, selling them wouldn't be easy as their liqudity here is diminishing.

So I hope you get my situation - trying to make the best with what I have 😉

[DGroves]

oh, i do understand more than you know.......................i'm simply trying to keep you aware that at some point projects take on a life of their own and consume way more money/time than they should

there's a saying that you can make a toaster fly if you spend enough money, but at some point it's cheaper to just buy the **bleep** plane