6,1 - Installed Samsung 970 Pro 1TB, is there a simple reason why I dont see a huge transfer speed?

Discussion in 'Mac Pro' started by Messy, Mar 8, 2019.

  1. Messy macrumors 6502

    Joined:
    Sep 5, 2010
    #1
    https://imgur.com/sLGTm7Z

    ^ Speed

    Any reason why I don't see even close to the rated speed that these drives can put out? I'm sure there's a simple explanation presumably something to do with lanes and such.

    If someone could just clear that up for me I'd be grateful. Seems a shame to have such a high spec drive and not be able to take advantage of the speed.
     
  2. tsialex macrumors 601

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #2
    You are limited with PCIe 2.0 speeds and just 4 lanes, so maximum throughput possible after overhead is just around 1500MB/s.

    Look here:

    Screen Shot 2019-03-08 at 13.14.37.png

    You can get the full diagram here: Did someone say block diagram?
     
  3. Messy thread starter macrumors 6502

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    Sep 5, 2010
    #3
    Cheers, as I suspected. What a shame, that's quite the way to cripple the speed.
     
  4. saulinpa macrumors 6502a

    Joined:
    Jun 15, 2008
    #4
    It was state of the art 6 years ago. One of many reasons people are pushing for a refreshed MP.
     
  5. Messy thread starter macrumors 6502

    Joined:
    Sep 5, 2010
    #5
    So a bit of an update, i'm now getting very poor speeds.

    Anyone shed any light on this?

    https://i.imgur.com/JEVNCxr.png

    [​IMG]
    --- Post Merged, Apr 16, 2019 ---
    Hmm, am I right in seeing that this is only using 2 lanes now?

    [​IMG]
     
  6. axrst macrumors newbie

    axrst

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    Apr 6, 2019
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    Greece
    #6
  7. Messy thread starter macrumors 6502

    Joined:
    Sep 5, 2010
    #7
    Yes I can see it's x2, not x4 which is why it's slow.

    I have been using https://www.amazon.co.uk/gp/product/B01CWWAENG/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

    In my OP it was running at full x4 speed.
    --- Post Merged, Apr 16, 2019 ---
    Also... that's not on a 6,1 is it?
     
  8. axrst macrumors newbie

    axrst

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  9. Messy thread starter macrumors 6502

    Joined:
    Sep 5, 2010
    #9
    Maybe worth replying to a thread that's more relevant to you then?
    --- Post Merged, Apr 16, 2019 ---
    @tsialex any ideas on this, gone from x4 to x2, no change in setup.
     
  10. tsialex macrumors 601

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #10
    1. Bad connection on the adapter connector, clean it and check for oxidation.
    2. Bad connection on the GPU, test with the original Apple SSD.
    3. Defective adapter, check with a new adapter.
    4. Defective M.2 blade, test the 970 Pro with another PC/MP5,1 that don’t need the Apple M.2 to standard M.2 adapter.
     
  11. Messy thread starter macrumors 6502

    Joined:
    Sep 5, 2010
    #11
    Well well well, very strange.

    I tore down the Mac, removed the PSU, both graphics cards, removed the RAM and SSD and then cleaned everything out using a can of air and reassembled...

    Now I have x4 speed! It's likely the Chinese Sintech adapter I would think as everything else just sits there not doing much.

    [​IMG]
     

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10 March 8, 2019