PCIe card that just provides power (SATA and/or GPU)

Discussion in 'Mac Pro' started by wonderspark, Nov 5, 2013.

  1. wonderspark, Nov 5, 2013
    Last edited: Nov 6, 2013

    wonderspark macrumors 68030

    wonderspark

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    #1
    Anyone know of the existence of a PCIe adapter card that simply takes the 75W from the slot and provides SATA power? I think it would be nice to power a bunch of (as in eight) SSDs with the power from my one unused PCIe slot #3, since I already have eight data connections remaining from my Areca RAID card.

    If there is such a thing, I'd love a link!
     
  2. wonderspark thread starter macrumors 68030

    wonderspark

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    #2
    Ooh, think I might have found one solution, even if it's a bit messy...

    [​IMG]
    Apricorn's drive array board would provide four SATA power slots, and if I needed to double that, I could just use SATA power splitters.

    It's an ugly solution, but it makes me think there must be a nicer (and probably cheaper) device out there that just pulls power from a PCIe slot.
     
  3. fabiovirgi7 macrumors newbie

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    #3
    Not so sure if this is gonna work though. :(
     
  4. wonderspark thread starter macrumors 68030

    wonderspark

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    #4
    It appears that it would work, if I could find one. It's an old product, so I will keep looking for a new (or at least available) alternative.
     
  5. VirtualRain macrumors 603

    VirtualRain

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    #5
    If you have an alternative solution for mounting and only need power, what about using one of the newer solo type cards…

    [​IMG]

    And just using one or more of these connected to the single SATA power connector it provides?

    [​IMG]
     
  6. MacVidCards Suspended

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    Hollywood, CA
    #6
    hmmm....if you could trace the pin outs and verify that all of the available 12V pins are connected, you could count on 75Watts from that little beast.

    Good enough to pick up the slack on a tight power fit GPU. And certainly easier than adding an X5 or external power.
     
  7. slughead, Nov 6, 2013
    Last edited: Nov 6, 2013

    slughead macrumors 68040

    slughead

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    #7
    There are mac drivers for the Sil3124, I don't know if that little "A" in Sil3124A will make any difference

    Edit: I can't find your card anywhere online. The one place that I could even find an MRSP put it at $670, btw.
     
  8. wonderspark thread starter macrumors 68030

    wonderspark

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    #8
    I had discounted this product because my mind was wrapped around pulling 75W from the slot, but I agree that this would totally work for the miniscule wattage of 8 of the latest SSDs. Thanks!

    I liked that big four drive unit because it meant splitting the power between four connectors. I did find it somewhere as 'discontinued / out of stock', but I forget how much it WAS available for... I thought it was $300 or so.

    I'm also loving the idea of using something like this for additional GPU power as well. If someone doesn't already make a solution to use that 75W, I see an opportunity!
     
  9. DanielCoffey macrumors 65816

    DanielCoffey

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    #9
    There is scope here for someone to do a PCI-E card with nothing on it but a 6-pin GPU socket.
     
  10. wonderspark thread starter macrumors 68030

    wonderspark

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    #10
    Or even a PCIe card with a 6-pin GPU socket, and eight SATA power connections, with a physical slide switch to choose between the two, so it could be used for either purpose. Now THAT would be cool!

    ----------

    Thinking more about this...

    Wouldn't getting a full 75W from a PCIe slot require a full x16 slot attachment, or are all the extra connections on an x16 lane slot just data? I'm thinking the two x4 lane slots probably don't give 75W, but if the x4 lane slots 3&4 *do* put out 75W in those connections, then I should just build my own power card. I mean, I'm a fairly skilled solderer... how hard can it be? :)
     
  11. TheDoc macrumors member

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    Mar 18, 2008
    #11
    This. I am very interested in making that work. Was checking out some PSUs the other day and I really don't want to deal with the cables and cutting holes in my box.
     
  12. wonderspark thread starter macrumors 68030

    wonderspark

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    #12
    Check it out! $14 for the board at the bottom of this page.

    I'm getting one, along with some connectors and other bits, and seeing what I can come up with. It's been a while since I graduated electronics school, but it will be fun anyway!

    ----------

    Got my answer to +12V pinouts on PCIe slot right here. This is going to work!
     
  13. TheDoc macrumors member

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    #13
    You might just have some orders coming your way :)
     
  14. ActionableMango macrumors 604

    ActionableMango

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    #14
    Maybe it is really that simple, but the PCIe guidelines for building a board imply otherwise. They state that you get 75W on an x16 slot and 25W for x8, x4, and x1 slots. It also states that even on an x16 slot you get 25W on startup, and you can only switch to 75W "after configuration as a high power device". I'm not sure what that means, but it sounds like the board needs to have a switch, logic, or communication of some sort in order to have the slot go high power.

    I don't pretend to understand this, but see page 20 of the PCIe 2.0 board design guidelines from PCI-SIG.

    In any case, for $14, it's probably worth trying. Even 25W will handle the original requirement (SATA power) and if it provides 75W, a lot of GPU people will be really happy.
     
  15. wonderspark thread starter macrumors 68030

    wonderspark

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    #15
    Nice, this is very helpful! I'll be open about my progress, and if anyone wants to help, the more brains, the better!

    I changed the title of the thread to make it more relevant to the thinking here. Right now, my goal is a switchable card that can run either GPU power @ 75W, or SATA power @ 25W. Let's see if that can happen!
     
  16. wonderspark thread starter macrumors 68030

    wonderspark

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    #16
    Along this line of thinking for a GPU power source, would you all agree that the end result would be an 8-pin plug (from the GPU) to dual 6-pin connections is the answer, such that one simply plugs into a standard 8-pin plug on the GPU, and on the other end, one 6-pin on the Mac Pro and one 6-pin on this new PCIe card? That way, the GPU sees the 150W coming from 2x75W sources, and there's no strange imbalances seen.
     
  17. ActionableMango macrumors 604

    ActionableMango

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    Sep 21, 2010
    #17
    This sounds right to me. In fact, there are already y-cables that do this (2x75W 6-pin to 1x150W 8-pin).
     
  18. wonderspark thread starter macrumors 68030

    wonderspark

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    #18
    So, I've put together a schematic for a test board. I was hoping some of you do this for a living, and can double-check my design for problems I might be missing, or just anything I'm not thinking about.

    As noted earlier, I found x16 lane slot PCIe bus prototype board, and I thought I'd build a 'simulation' of a GPU pulling about 75W from an open PCIe slot by loading it up with resistors and using all three +12v lines from the PCIe slot 4.

    In this attached schematic, I have 12v at 6 amps, and the total wattage from 18 resistors comes to 72W. Each resistor is a 5W variant, with 1 ohm resistors each seeing 2v / 4W / 2A, so none should melt down. I plan to add either a 6.3 or 8 amp fuse in the line, just for protection, should something go wrong.

    My theory is that I should be able to build this board, stick it in slot 4, and I'll see 6 amps on the iStat sensor for that slot.

    If that is the case, then I'll proceed to building a board with the three +12v lines along with 3 ground lines going to a 6-pin connector, which would then attach to the second side of a y-connector that makes up two 6-pins to a single 8-pin, which then would connect to a GTX 780 for example.
    (For a GPU with one 6 and one 8 pin aux wires, the 8-pin goes into the GPU, one of the 6-pins goes into the second power plug on the backplane, and the second 6-pin goes into the plug on this PCIe card. The first 6-pin-to-6-pin goes directly from the backplane to the GPU.)

    In this manner, there should be 300W drawn to the GPU from:
    PCIe slot on GPU (75W)
    PCIe slot on this special card, 6-pin A (to 8-pin on GPU, 75W)
    Aux wire #1 on backplane (6-pin B, 75W)
    Aux wire #2 on backplane (6-pin, 75W)

    I hope you followed along with that, and it makes sense.

    If that works, then I'll make another board with a switch, and set it up for eight SATA power connectors, so that really ambitious people can connect up to eight more HDDs or SSDs internally. That one is a little bit more tricky, since it involves converting +12v down to +5v, and I haven't figured out that schematic yet. Just seems like more people want another 75W for GPUs than would want more SATA power connections at the moment. :)
     

    Attached Files:

  19. DanielCoffey macrumors 65816

    DanielCoffey

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    #19
    Um... is that board just PCI? Don't we need PCI-e?
     
  20. MacVidCards Suspended

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    #20
    Note the tab at front, PCIE
     
  21. wonderspark thread starter macrumors 68030

    wonderspark

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    #21
    Well, worst case is I use this PCIe-to-PCI adapter for the prototype:
    [​IMG]

    Just another $38.
     
  22. DanielCoffey, Nov 7, 2013
    Last edited: Nov 7, 2013

    DanielCoffey macrumors 65816

    DanielCoffey

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    #22
    The one I see at the bottom of the page is listed as PCI bus and has the tab at the back. Am I missing the correct one ?

    EDIT : here is a fun page with a PCI-E fpga board... http://www.fpga4fun.com/PCI.html

    Googling "pci-e dragon board" shows some bare boards too.
     
  23. TheDoc macrumors member

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    Mar 18, 2008
    #23
    Hey wonderspark, any news here? Not that I'm waiting on the edge of my seat or anything... :)

    Just starting to look at some power-hungry GPUs considering the sales we're going to see tomorrow.
     
  24. Pompiliu macrumors 6502a

    Pompiliu

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