Resolved eGPU enclosure + M.2 PCIe to PCIe 3.0 x4 Adapter + NVMe SSD

Discussion in 'Mac mini' started by adamk77, Apr 2, 2019.

  1. adamk77 macrumors 6502a

    adamk77

    Joined:
    Jan 6, 2008
    #1
    I just canceled my order for the Samsung T5 external SSD because I want to see if this is a viable option. It's late, past 5 AM here and I'm dealing with a bad case of insomnia, so maybe I'm not thinking straight.

    A Thunderbolt 3 PCIe NVME SSD Enclosure (Cube) on Amazon is $200. Instead of this, I am thinking an eGPU enclosure like the Sonnet (also $200), with a M.2 PCIe Adapter ($22 - many others out there for cheaper), with a NVMe internal SSD plugged into it should work.

    Ignoring the benefits of aesthetics and size of the SSD enclosure, the benefit of the eGPU enclosure is that it can also be used as an... eGPU enclosure. And there are even M.2 PCIe adapters like this that take 2 SSDs (M.2 NVMe M Key & M.2 SATA B Key).

    There is also an enclosure like the Akitio Node Duo that has 2 PCIe slots inside, though I haven't looked into it much.

    Am I missing something obvious here?
     
  2. Stephen.R macrumors 65816

    Stephen.R

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    #2
  3. Trips macrumors newbie

    Trips

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    #3
    I see where you're going, and I like it. Im also awake and shouldn't be lol.

    But, one reoccurring theme I've seen with all the reviews and reports via eGPU usage is that the performance is diminished versus what an internal GPU can do on similar systems. Such is not the case for nVME SSD over TB3. They seem to have no problem performing 1:1 versus internal storage speeds. So it makes me wonder if running the nVME SSD within the eGPU and sharing that PCI lane will also impact its performance in the same way the eGPU is impacted. But I admit, I am not up to speed (no pun intended) on how all of the data is transferred in that scenario in terms of the PCI Bus lanes, and the bus saturation overall. Maybe someone else who knows more can chime in to that end?
     
  4. adamk77, Apr 2, 2019
    Last edited: Apr 2, 2019

    adamk77 thread starter macrumors 6502a

    adamk77

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    #4
    The reason to go with the eGPU enclosure in lieu of the case you linked is because that case is specifically for NVMe SSDs.

    I'm trying to see if I can kill two birds with one stone. The Akitio Node Duo looks interesting. It has two PCI-e 3 x2 slots. Thunderbolt 3 is limited to 40 Gbps, so that would mean each PCI-e in that enclosure can handle around 20 Gbps though in practice it's less than this (Wikipedia says for PCI-e 3 x2, it's 15.76 Gbps to be exact).

    Here's what I'm thinking:

    1st PCI-e slot for an eGPU (RX 580)
    It will be only a 2-lane PCI-e, but I'm thinking this should be fine with an external monitor (https://egpu.io/forums/mac-setup/pcie-slot-dgpu-vs-thunderbolt-3-egpu-internal-display-test/) and I should be able to run 4K at 60Hz. It won't be used for gaming.

    2nd PCI-e slot for the NVMe SSD
    I know that NVMe SSDs can take advantage of more than 15.76 Gbps. But this is still far better than a SATA SSD that maxes out at 6 Gbps.

    Can anyone see why this wouldn't work?
     
  5. alphaod macrumors Core

    alphaod

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    NYC
    #5
    From your first line of the OP, I assume you looked at the Samsung T5 because you're looking at storage right?

    I have a 2TB Samsung T3 I've used for almost three years now. Best purchase I made. It's small, very fast, and very reliable. Even supports TRIM and everything.

    What you're suggesting seems all nice, but I think is a big waste of time of money for something that can resolved with a simple solution like the T5 that you almost got. Using an eGPU will definitely lower the bandwidth on the Thunderbolt 3 interface for the NVME SSD that you'll probably be better off getting the T5.

    And if the T5 is too slow you can always look at the X5.
     
  6. Stephen.R macrumors 65816

    Stephen.R

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    #6
    They’re not only 2x rather than 4x like most GPU slots, they’re half-length.

    On the compatibility page Akitio list a bunch of special-purpose cards and then this at the bottom:

    A number of other eGPU cases (eg the OWC ones) don’t even include TB3 daisy chain ports because the GPU will saturate the connection.

    What you want to do may technically work but it’s not going to work well
     
  7. adamk77 thread starter macrumors 6502a

    adamk77

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    #7
    I thought that's what I wrote, "Two PCI-3 x2 slots" -- or are you talking about something else?

    I don't believe having 2 vs 4 lanes will matter when the eGPU is used with an external monitor. This guy in this link is running two RX 580s off of the Akitio. And he says that in MacOS, it was plug-and-play. My guess is that it's listed as not being supported because you need to hook it up to an external PSU as the Akitio only comes with a 150W power supply.

    If I had the extra funds, I'd give this a go and see if I can get an eGPU + NVMe SSD in one bang, but the experiment is too rich for me.
     
  8. Stephen.R macrumors 65816

    Stephen.R

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    #8
    The case only supports half-length PCIe cards - don’t most mainstream graphics cards require a full-length slot? The rx580s I’ve looked at are all ~10”, but a half length slot is only 6.9”)
     
  9. adamk77 thread starter macrumors 6502a

    adamk77

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    #9
    I think there is only enough contacts for the number of pins in a PCI-e x2. The guy in the link clearly states that he has two RX 580s enclosure, so it must fit. Maybe he has these https://www.msi.com/Graphics-card/Radeon-RX-580-8G-V1/Specification -- it's 7.8" and the max that the Akitio Node Duo will take is 8.66" according to their specs.

    But I think my question has been answered. In my haste, I didn't read the thread all the way through. He posted a follow up, stating:

    I changed the 2nd RX 580 eGPU out for a SSD. The drive is HP EX920 NVMe 1TB mounted on an M.2 PCIe adapter. Total cost of the 1TB drive and adapter is $172. This is a significant saving when compared to $800 Apple wants for an upgrade to 1TB internal drive.
    He also shared the benchmark results of the SSD.

    1138 MB/sec read, 1394 MB/sec

    The bandwidth is limited by the 2 PCI-e lanes, but that's much faster than the Samsung T5. This also means you can buy a cheaper NVMe SSD like this Crucial 1TB for $105 instead of the Samsung which is $250. It's slower than the Samsung, but still more than enough for the 2 PCI-e lanes at 2000 MB/s read, 1700 MB/s write.
     
  10. adamk77, Apr 3, 2019
    Last edited: Apr 4, 2019

    adamk77 thread starter macrumors 6502a

    adamk77

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    #10
    Just a quick update in case this will be helpful to anyone in similar needs.

    I got a reply from the gentleman from the eGPU.io forum who's built this exact configuration and received a very helpful reply. I think that this can be a great solution if your needs are like mine -- no gaming, just a better dedicated GPU and a fast external SSD.

    The setup is:
    • Akitio Node Duo ($375)
      • Has two PCI-e Gen3 x2 slots
    • RX 560 ($100 - $150)
      • Will fit in the enclosure and does not require an external PSU whereas the RX 580 I was originally considering will require an external PSU, adding to cost and complexity, subtracting from aesthetics.
    • M.2 PCI-e Adapter ($15-$20)
    • 1TB NVMe SSD ($105)
      • Don't need a really fast one because you're limited by the 2 PCI-e lanes but will be much faster than a Samsung T5.
    The setup can be had for around $600 - $650. You get better dedicated GPU power that the Mac Mini sorely needs for certain applications. Additionally, you also get a fast external NVMe SSD that's much more performant than the external USB 3.1 SSD. All of this is inside a single enclosure.

    The reason I started looking into this is because I noticed that the simulator in Xcode was sluggish with the iGPU. I learned that Xcode can fully leverage the eGPU. I also wanted a SSD that's faster than what the USB 3.1 could offer.

    It's definitely a compromise. Below are some alternative configurations that I've been mulling over.

    For $600 you can do this. The compromise here is a faster GPU but a slower SSD.
    • Sonnet eGPU enclosure ($200)
    • RX 580 ($200)
    • 1TB Samsung T5 ($200)
    For $900 you can do this and optimize for speed if cost is less of a concern.
    • Sonnet eGPU enclosure ($200)
    • RX 580 ($200)
    • 1 TB Samsung X5 ($500)
     
  11. DRDR macrumors member

    Joined:
    Jul 23, 2008
    #11
    I realized an external enclosure myself:
    https://forums.macrumors.com/threads/diy-thunderbolt-3-ssd.2157610

    Sonnet does offer multiple PCI enclosures, but they are not cheap. There are also some expensive dual PCI-to-NVME adapter cards out there. But they are very expensive and information is a bit lacking. You can find more information at barefeats.com: Amfeltec PCIe 3.0 M.2 Dual-Slot Carrier Board
     
  12. joevt macrumors 6502

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    Jun 21, 2012
    #12
    Search for threads regarding the HighPoint 7101A, the Amfeltec PCIe 3.0 M.2 carrier cards, I/O CREST SI-PEX40129 or IO-PCE2824-TM2, and the new Sonnet M.2 4x4. They are expensive because they need a PCIe switch chip to support more than one device. The IOCrest one might be cheaper because it uses an Asmedia bridge chip instead of a Broadcom PLX bridge chip (and it supports two M.2 drives instead of 4, and only has x8 upstream instead of x16)?
     
  13. kaikaidragonz macrumors newbie

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    Oct 22, 2014
    #13
    let us know how this works out!
     

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12 April 2, 2019