Help with power delivery [STX+GPU]

Discussion in 'Concepts and Ideations' started by Ross Siggers, Nov 10, 2018.

  1. Edward78

    Edward78 Cable-Tie Ninja

    That is a mITX case, of course it will... I have plans for a mATX version with 5 slots for the duel gpu in the last MB slot just need to spend around $500 at protocase...
  2. Phuncz

    Phuncz Lord of the Boards
    Moderator SFF Purist Gold Supporter

    You'd better spend that money on 3-slot case and a better single GPU card as it will be easier and better. I've had to let go of dual GPUs as well because it just isn't getting the support it needs these days. Some games will stutter, some games won't even use it, some games only have < 20% performance increase.
  3. Edward78

    Edward78 Cable-Tie Ninja

    I mean the ones with fans, where it exhausts the hot air out the back...
  4. Zackmd1

    Zackmd1 Airflow Optimizer

    People seem to forget about the Add2Psu product...

    Pretty much every STX board has a SATA power connector. Convert the SATA power to Molex 4 pin using something similar to this...

    And then you have your signal to turn on a pico psu that can be used to power the GPU. So basically you will have a 19v power supply connecting to the barrel connector of the stx board and to the pico unit. An hdplex or dynamo mini connected to the add2psu using the sata port as a signal source and there you go, a full GPU power solution for STX with switched and filtered 12v power.
  5. Ross Siggers

    Ross Siggers Average Stuffer
    Thread Starter

    This looks like a cool product, but if I'm understanding this correctly, you're using an example of a powered motherboard, to send a signal to the Add2PSU, which will turn on the Pico, thus powering the PCIe for the graphics card. But in my system... the idea was that the pico is powering everything; It receives the external power, has a dedicated PCIe header on it for the graphics card, and the motherboard power will come from either the 24-pin itself, or the 4-Pin cpu plug, via a custom cable, to adapt it to DC barrel.

    This makes me suddenly think about @Choidebu 's suggestion of using 5v from the fan header to trigger the pico; That would also require the board be independently powered? Or does the fact it's switching to a ground make a difference

    For someone with literally no electrical knowledge, this is frustrating. It's the only part of the build I don't have the ability to solve myself, combine that with real life getting in the way and this build has been gathering dust for literally months, it's really fucking annoying.
  6. Thehack

    Thehack Shrink Way Wielder
    Bronze Supporter Creator

    #46 Thehack, Apr 14, 2019
    Last edited: Apr 14, 2019
    You cannot use the PICOPSU to power the motherboard. You cannot use the 24pin to power the motherboard. You cannot use the 4 pin CPU to power the motherboard. You can use the PICOPSU to power the GPU.

    The motherboard takes 19V externally. All PICOPSU is designed to output 12V, 5V, and 3.3V for the motherboard. An STX motherboard takes 19V. 19V.

    The GPU takes 12V internally.


    This is what you need to do:

    1. You need a M.2 to PCIe riser with auxiliary power. M.2 can only do 25W. You need about 50-75W on the riser. Buy one where you can plug in an external 12V.

    2. You need a 19V brick, this powers the whole system.

    3. You need a 19V to 12V converter, this powers the GPU side. This can be a wide input PICOPSU, a direct DC-DC step-down converter, HDPLEX, whatever. It just needs to take 19V in, and put out 12V. You can use whatever you want. Just check the spec sheet where it says "input" it has 19V (or a range 16-24V for example) and it spits out 12V on the other side.

    4. You need a way to turn off the 19 to 12V converter system. This can be done a couple ways:
    • A dumb switch. You flick it, it turns on the 12V. You flick it off, it turns it off.
    • A smart load switch. Requires a custom PCB. I do have carry the Distro 400, which can act as a load switch but it's damn overkill for this usage. It can take any positive signal (12V) and then turns on.
    • A solid state relay. Essentially same thing as a load switch, but they're an off the shelf part that requires you to solder and/or make connectors.

    Note, the meaning of a switch is not a button. A "switch" is a device that connects a circuit together when activated. It is not a button. It is a device that connects circuit.

    If you have the Dynamo 360, the Dynamo 360 should be able to act like a load switch AND a DC-DC converter in one unit.

    First you need to confirm what kind of SYNC signal the 360 needs to turn on. I believe it is a 5V signal. SO bear with me here.

    AC-DC ===> DYNAMO 360. You got power to the system.

    To power motherboard, DYNAMO 360, pass through output ===> STX motherboard DC in. Bam. You're done with powering the motherboard side.

    To power the GPU, DYNAMO 360, PCIe OUTPUT ===> Powered Riser and GPU PCIe. Bam. You're done with powering the GPU.

    To turn the GPU on/off, you need to figure out a way to SYNC the Dynamo 360. You should be able to take the 12V lead from the fan output, and attach it to the SYNC on the Dynamo. This tells the Dynamo, yo bro, the PC is on, time to output 12V. This assuming the Dynamo just wants a "high" signal, 5V+ to turn on.

    There. End thread.

    DISCLAIMER: This way is not guaranteed to work. It should work in most situations, but sometimes, you get a latching issue. Through some complicated electrical explanation, the Dynamo 360 may not turn off due to a the way the motherboard traces are set up.
    Soul_Est likes this.
  7. Ross Siggers

    Ross Siggers Average Stuffer
    Thread Starter

    #47 Ross Siggers, Apr 14, 2019
    Last edited: Apr 14, 2019
    I'm busy at the moment, so I'll come back for a proper read this evening. But I skimmed the post and it was hard for this not to catch my eye...

    I'm using an ASUS H110S2 board. It accepts both 12v and 19v input.
  8. Thehack

    Thehack Shrink Way Wielder
    Bronze Supporter Creator

    In that case, it is an exception to most boards.

    Regardless you should still use the 19V function of the Dynamo 360 instead of using 12V.

    This is because using a picopsu, 24pin, causes more grief cause you have to rewire it or use a dumb Add2psu board. Just the dynamo 360 is suffice. Especially if you already own a 19V brick.
  9. W4RR10R

    W4RR10R SFF Lingo Aficionado

    I don't know about the ASUS mSTX boards but on the Asrock one's the sata only has 5v that 2.5 inch drives use, no 12v.
  10. Thehack

    Thehack Shrink Way Wielder
    Bronze Supporter Creator

    Are you sure no 12V? SATA drives don't use 3.3v nowadays but this is the first I've heard of no 12v.
  11. Kmpkt

    Kmpkt Innovation through Miniaturization

    A lot of these boards (ie. Thin ITX) actually have 12-19V wide input but don't advertise it. I've sent a PM to AsRock regarding this but have yet to hear back from them.
  12. W4RR10R

    W4RR10R SFF Lingo Aficionado

    Yeah page 23 of the DeskMini A300 manual.
    Thehack likes this.
  13. Ross Siggers

    Ross Siggers Average Stuffer
    Thread Starter

    #53 Ross Siggers, Apr 15, 2019
    Last edited: Apr 15, 2019
    Just to lay components out, because I don't think I ever did so;

    ASUS H110S2 stx
    i7 7600T (35w)
    2x4Gb ram
    Gtx 1060 mini
    KMPKT Mini pico
    DELL external 230w brick

    Case is a Dreamcast, 2.8L. Stupidly ambitious for a first build I know :/

    I've only quoted the latter part of the post, am I right in saying the first part was written with a 19V only motherboard in mind? Happy to be corrected, you were saying to have separate 19V feeds for the mobo and gpu, with one having a 12V step down.

    I did originally order a 360, but there was no way it was fitting in the case without compromising...everything. I used it to test the system before exchanging it for a Mini. But whilst I had it, I did have it wired up in the same straightforward manner you're describing;

    Brick --> 360 --> Motherboard.
    Makes perfect sense, hence the DC cable supplied in box. What I was enquiring about a while back, was if it was possible to make a PCIE-2-DC cable, like that one, for use with the Mini and it's 'cpu' labelled output, as that would be a 12V wouldn't it?

    Regarding the GPU, I do have a powered riser(sata) already, I need one that isn't shit, but that's besides the point XD

    If the motherboard is receiving power and gets switched on, would the riser not automatically trigger the card to turn on with the rest of the system, via the M.2? Provided it has any additional power it requires, in the case of a 1060.

    What I was trying to wrap my head around, was how to get the motherboard to turn on using a Mini, instead of a 360. Which from what I understood it could only do with a signal, from....the motherboard it's supposed to be powering :/ Is this a complete dead end idea, no way around it, don't be stupid, etc? Because provided the DC cable above can be bought/made, that's the only thing in question?

    W4RRIOR actually made a very similar build, but he squeezed in a 360 so didn't run into this issue it seems.

    As always, apologies for any miscomprehension.
    (And multiple post edits :p )
  14. Thehack

    Thehack Shrink Way Wielder
    Bronze Supporter Creator

    1. The issue is not turning on the gpu. It's turning it off. This whole discussion is really about turning off power to the gpu. If you give it 12v, when the pc is off, the gpu has unintended side effects of power applied like the fan running at 100%. We're discussing in terms of turning it "on" but we're more concerned of it being able to have an "off" state.

    2. An stx motherboard works opposite of a regular motherboard.

    you only apply power to a regular motherboard, when it turns on. In the case of STX, power is always applied for it to work.

    3. If your motherboard can take 12V, then you don't need an hdplex anything. Run a full 12V build.

    You will need a dc solid state relay. Motherboard DC fan header connected to a solid state relay.

    When power is on, the solid state relay connects 12v power to the gpu, power is applied. When the motherboard is off, the solid state relay disconnects power and the gpu can have an "off" state.

    If you don't care that your gpu doesn't have an "off" state, just connect 12v to everything and you can run it just fine.
    Ross Siggers likes this.
  15. Ross Siggers

    Ross Siggers Average Stuffer
    Thread Starter

    #55 Ross Siggers, Apr 15, 2019
    Last edited: Apr 15, 2019
    Right okay, thanks for clarifying! So getting it started isn't an issue XD I'll look at the solid state relays in a bit, I don't feel like turning the system off at the wall every time...

    If I were using a DC converter to get the brick output to 12V, what would that mean for a gpu like the 1060 that requires additional power. Is it simply splitting the converter output cables to feed the mobo and gpu at the same time?

    The converters I've seen seem to be pcb's with solder points for cables, so the above sounds kind of janky :S
  16. Thehack

    Thehack Shrink Way Wielder
    Bronze Supporter Creator

    Yes. You connect the ac-dc converter straight to the gpu. But then it won't have be able to go "off."

    Now the if you add a solid state relay between the ac-dc converter and the gpu, the solid state relay is an on/off switch. It has a lead for the control signal, which in this case may be 12v.

    However, I have found that in certain situations, the solid state relay gets latched on depending on how how the traces are handled by the board.
  17. Choidebu

    Choidebu King of Cable Management

    If this is your first build, then frankly you got a lot of understanding to catch on...

    If you've got the parts all sorted out, at least motherboard+cpu, ac/dc brick, some display, wire it all up outside the case on a mat or something, turn it on and experience it for yourself.

    Stop the gpu and m2 riser thingie, understand basic stuff first...
  18. Ross Siggers

    Ross Siggers Average Stuffer
    Thread Starter

    #58 Ross Siggers, Apr 16, 2019
    Last edited: Apr 16, 2019
    @Choidebu I suppose I'm stuck thinking of things in a very traditional way, layout wise. 'ATX-brain' lets call it XD The system has been powered on exactly as you describe, open bench no gpu, back when I had a 360. Just to test the components, I know it works set up that way.


    But there's absolutely nothing interesting about the build as pictured above. It's not even ambitious for a first time SFF builder, no doubt everyone would agree. What makes it worthwhile to me is a dedicated GPU. And what makes it impressive to me is the lack of space wastage. I'm not trying to defend my ignorance, I'm just very determined to get something working without making huge compromises.

    If I were to start again from scratch, which I'd rather not, I would use larger console(fat PS2, og Xbox?) as the case, and put a 360+AC-DC directly inside the case. I'm aware that would be more straightforward XD

    @Thehack Regarding motherboards not GPU's....You previously mentioned the differences in power delivery between ATX and STX; where the latter are constantly powered. Is that what allows it to be turned on when connected to the 360 by only the DC lead, as above. That is to say, is the power cable itself the trigger. And if so, is there any reason why the same principle wouldn't work with a Mini and the correct adapter cable?

    Lets say the above only works with a 360. Would a feasible layout be;

    external brick -->Dynamo 360 -->Motherboard
    Powered M.2 riser + 360 PCIe additional power --> GPU
    DC solid state relay to turn the GPU off.
  19. Thehack

    Thehack Shrink Way Wielder
    Bronze Supporter Creator

    #59 Thehack, Apr 16, 2019
    Last edited: Apr 16, 2019
    The DC cable is not a "trigger."

    In stx motherboards, the power control turns the system on. Think of it as a store.

    STX: the workers (electricity) wait at the door. When you press the button, the door opens and they get to work. There is a controller that handles opening the door when you turn it on.

    ATX: the door is always opened but there are no workers there. When you press the on button, you send the worker to the store and they get to work.

    The gpu works like ATX.

    The mini 160 can trigger on, but there's no point in adding multiple complexity to the system

    You need a circuit to turn it on, like Add2psu. If the system can use 12V, a 12v ac-dc unit and a single solid state relay will do the trick. When you add a trigger circuit to turn on the Mini, you are literally adding a solid state relay (Add2psu is a solid state relay circuit).

    Why use 3 components when 2 will do?


    You do not need a relay with the dynamo 360. It has a "sync" input which acts like a solid state relay. I believe given 5v, the sync signal turns on the pcie output.
    Ross Siggers likes this.
  20. Ross Siggers

    Ross Siggers Average Stuffer
    Thread Starter

    #60 Ross Siggers, Apr 16, 2019
    Last edited: Apr 16, 2019
    So it's all handled 'on-board' with STX, no pun intended XD Nice analogy, thanks :) So then, the solid state relay is only required when using no psu(DC step down board), or a smaller psu such as a mini that has I guess doesn't have sync capabilities on the pcie?

    Does that mean, in theory, the above layout with a Mini in place of the 360 would work? I have a jumper for the Mini to run it unplugged.