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The HP Community is where owners of HP products, like you, volunteer to help each other find solutions.
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HP Z840 Workstation

Hi there


We disconnected cables from the motherboard, the power switch one

And can't find anywhere, how to connect

Could you please kindly point us to the motherboard manual, with relevant information

Or could someone take a picture of it and kindly share 🙂





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Welcome to the HP Support Community  @WIce22888 


See if these videos help???


HP Z840 Workstation - FRU Remove/Replace Videos:








HP Z840 Workstation - System Board:





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Thanks for your answer RE051ST


Very good resources thankyou 

but it's not solving our issue,

The thing is that our Cable is not in one piece as shown on the video, not just plug and end of the story 🙂

And to connect them in the right order to "Front UI/power button/LED connector on the board"

We would need to know the description for each pin. 

This would not be an issue with any other motherboard sins they usually come with a detailed description of each pin

But z840 is not the case....

So wondering if there is any doc describing this...







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Ooooohhhh.... nice example of the value of documenting before disconnecting (having done this myself).  Here's some ideas:


I have never seen the plug end on these workstations broken up into multiple sub-plugs.  You can find this cable, new, on eBay and it does not show the plug end to be in two or more parts.  Here is a picture of the plug end from that ad:




There obviously are more wires there than just for an on/off switch.  There is that, and the speaker, and the wires for a "hood sensor", and the ambient air sensor wires.  The colors may help you if your plug is actually in two parts.  There are tiny printed bits of info on the motherboard... get a flashlight and a magnifying glass.


Another idea... look at a Z640..... very similar parts and placement of motherboard headers.


And, look up my old document via a google for "xw6600 pinout", and download that top .doc version, and take a look there for some added details.  Some of the engineering has not changed.

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Thanks for replay

It's more disassembled rather than broken

not sure why,

I was intensively looking for any cabling on eBay and Amazon for z840, asking for distributors etc, none of them has it for sale...

and not sure if HP sells them too...


I know these motherboards are not standard, but still why shouldn't be such documentation in the manual as any other motherboard has worldwide...

thanks for the idea, will check xw6600 pinout




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I put the part number on the picture but now realize you can't see the picture until a moderator releases it.  Racy cable pictures, you know......




HP might respond.... why in the world would you take the cables apart without documenting where they came from?  They don't put PCB layouts of the motherboard in the manual either.  Just saying.....   And, your answers just might already be printed on the motherboard by each header.  Have you looked?  I found quite a few answers to pintout quesitons that way on HP motherboards.  The printing will be very small.

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It was cracked for some reason, and I didn't know it's not documented anywhere.... Someone has been too lazy I guess 🙂


nothing on motherboard

(Screen attachedSkype_Picture_2019_03_16T20_52_02_749Z.jpeg)

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Dude, if you're planning on building up a home-made Z840 from a used motherboard just say so.  You have a complex job ahead.  If the motherboard is virgin and not yet "branded" (= "tattoo") then your job will be virtually impossible.  The printed triangle is at pin 1.  The missing pin is the "key" for the filled hole in the plug on the cable.  Plan on buying cables, not making them, to avoid disaster.  The engineering has not changed a huge amount.... get my doc.  Also, here is a link you'll want:




You've got a lot of resources via Google to go search for...

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What exactly makes you think I'm building it from scratch ??

To be honest, I'd be glad if I could put it in some bigger box with bigger PSU, but I think its too much hassle 



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