Concept Help with power delivery [STX+GPU]

Ross Siggers

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Nov 10, 2018
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A couple of parts I need to get. For the motherboard 19v and maybe the sync, I have plenty of old pc parts I can butcher for the right sort of wire.
 
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Ross Siggers

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Nov 10, 2018
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Well shit. I better order those parts and give this setup a try :eek:

I actually want a better riser cable, so for the sake of testing the system 100% as it will eventually be, I'll bin my old one and test when I get another one delivered.
 
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Kmpkt

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Feb 1, 2016
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I've tried splitting the DC before the PSU before and it resulted in a completely fried NuC. I'm not sure this is the best idea but perhaps @Thehack could offer better advice.
 

Ross Siggers

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That's one wiring job I trust myself not to mess up hopefully! The HDplex pcb I have labels the cables
 

Ross Siggers

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Nov 10, 2018
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So I got my parts in :) Apologies for the delay, I had to fly abroad at short notice :/

I'm trying to make a splitter for my fan header, so I can tee off the signal wires for the add2psu whilst keeping the header functional as normal. It's the only one on the board :eek: The chassis fan header is 12v, the relay on the add2spu says 12v on top...

But I'm seeing conflicting info as to which pin is which on a molex connector. I looked at the traces on the pcb for the add2psu and only the two pins on the LEFT of the image are actually connected, next to the relay, labelled pins 1 and 2;



This diagram says the outer pin should be a 5v based on visual cues...



Whereas THIS chart seems to say it's the 12v, based off of the pin numbering written on the board...



Uhhhh...wat?? Can someone please confirm what it actually is?
 
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Thehack

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So I got my parts in :) Apologies for the delay, I had to fly abroad at short notice :/

I'm trying to make a splitter for my fan header, so I can tee off the signal wires for the add2psu whilst keeping the header functional as normal. It's the only one on the board :eek: The chassis fan header is 12v, the relay on the add2spu says 12v on top...

But I'm seeing conflicting info as to which pin is which on a molex connector. I looked at the traces on the pcb for the add2psu and only the two pins on the LEFT of the image are actually connected, next to the relay, labelled pins 1 and 2;



This diagram says the outer pin should be a 5v based on visual cues...



Whereas THIS chart seems to say it's the 12v, based off of the pin numbering written on the board...



Uhhhh...wat?? Can someone please confirm what it actually is?

Look at a real life connector. Notice the color of wiring.

Imagine it being plugged in.

Notice the location of the colors. Yellow is 12V and red is 5v.

No need to mess with pin numbers.
 
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Ross Siggers

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Nov 10, 2018
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In that case being on the right had side of the connector(with the notches upwards) would make it the 5v, whereas my feed from the mobo is 12v. Would this be a problem, or does it just depend on if the relay can handle it, being marked up as 12v.
 
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Choidebu

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Aug 16, 2017
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So I got my parts in :) Apologies for the delay, I had to fly abroad at short notice :/

I'm trying to make a splitter for my fan header, so I can tee off the signal wires for the add2psu whilst keeping the header functional as normal. It's the only one on the board :eek: The chassis fan header is 12v, the relay on the add2spu says 12v on top...

But I'm seeing conflicting info as to which pin is which on a molex connector. I looked at the traces on the pcb for the add2psu and only the two pins on the LEFT of the image are actually connected, next to the relay, labelled pins 1 and 2;



This diagram says the outer pin should be a 5v based on visual cues...



Whereas THIS chart seems to say it's the 12v, based off of the pin numbering written on the board...



Uhhhh...wat?? Can someone please confirm what it actually is?

Read the diagram. It's the plug. Your add2psu is the header/socket.

Anyway - just look at wire color.
 

Ross Siggers

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Nov 10, 2018
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Got all the parts in, but my soldering iron kit is utter garbage and not up to the task XD

Time to get a new one before I can make the power cable :\
 

Sean Crees

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Jan 1, 2017
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Got all the parts in, but my soldering iron kit is utter garbage and not up to the task XD

Time to get a new one before I can make the power cable :\

I'm in the process of making a case for just such an arrangement, STX motherboard + GPU utilizing the HDPLEX 400w as an internal PSU to power the motherboard, now i just need a buck converter to convert 19v to 12v for the CPU PCI-e power with sensing to turn off when the computer turns off.

I havn't read through this entire thread, but an update to the original post on the progress of this project would be really appreciated.

In my own search, i came across this: https://www.pololu.com/product/2885 which has all the capabilities needed, i just am not sure how to push 1v to the "EN connector" when the system is shut off to put the unit into power down mode.

With the SFFLAB.com store about to sell ASrock stx motherboards as standalone (without the case it normally comes with), i feel like this is an overlooked aspect of STX builds that someone really needs to solve with a product to fill this niche.
 

Ross Siggers

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Nov 10, 2018
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Hi @Sean Crees well, I have an update, I'll try and edit everything into the original post tonight :)



^ Dual power cables soldered in.




^ My incredibly professional, definitely-not-twisted-together signal cable for the Add2psu XD Testing purposes only, I'm going to make a better cable on final assembly.




^ IT'S ALIVE !!!!!
I don't have a suitable gpu atm to test it's PCIe output, so for proof of concept, I'm powering the ssd and the riser using the sata header




^ And here's the whole thing set up, apologies for the cramped workspace. System runs and boots fine, I've used Furmark, but I'm yet to do a cpu stress test like Aida. I'm keen to know if I need a heavier-duty power cable for the motherboard(far left of the image), but the CPU is 35w TDP so total power draw on full load shouldn't be too much higher.
 
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Ross Siggers

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Nov 10, 2018
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I'm going to run a few stress tests but if all goes well, I can start to look at cutting a space in my case to mount the KMPKT, and shorten all the wires as much as possible to reduce clutter.

In the meantime, I'd really like to thank everyone who posted in this thread, for their seemingly limitless patience with me ? I don't know how you managed it ?
 

Ross Siggers

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Nov 10, 2018
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@Kmpkt How much space could you advise as a minimum to leave next to the heatsink? It got fairly hot to the touch when using the PC on an open bench last night, and currently it's almost touching the motherboard. I'm worried about it getting hot enough to radiate heat and damage the board, does it get that toasty under load?

I can shift it back maybe 1-2 more mm....if I mounted it angled, outwards at the bottom and leaning inwards at the top, I could probably get that gap up to 3-4mm. It'll have exhaust air from the cpu hitting it and going up that gap, whatever the final size of it is.

Any thoughts :)



 
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Kmpkt

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Yeah I'd be cautious and maximize the distance for heat to dissipate. Keep in mind you may also have to worry about plastic damage if the heatsink gets too hot the way you have it nestled in the Gamecube chassis.
 
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Ross Siggers

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Nov 10, 2018
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Okay cool, I'll see what I can do to move it away slightly :) It was always planned to go there, but I put it facing inwards to try and catch some of the cpu airflow, and keep it away from the plastic walls.

I'll cut a little bit more room around it too. This was more for drafting out positions, when the add2psu is hard mounted I can open the surrounding plastic up a little.
 

Ross Siggers

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Nov 10, 2018
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Sacrifices were made, such as removing the latches on the connectors to push it as far outwards as possible. I also dremelled out a notch for one of the taller capacitors... But it's done, and there's a little breeze vertically over the heatsink when the system is running. Air also does get into the cavity behind, so the components on the opposite side aren't heatsoaking like you'd think, but I still intend on cutting away more. I wanted to keep it enclosed for structual rigidity, but the case seems sturdy enough when screwed shut, so I should be okay to open it up for more airflow.







But aside from shortening the power cable it's all crammed in there and the system runs happily. Never thought I'd see the day! I need to do load tests, but that'll just be to assess thermals. The components themselves work perfectly together, and I still have the PCIe power free for the planned gpu further down the line :)
 
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