USB 3.1 on 5,1 Mac Pro

Discussion in 'Mac Pro' started by pierre1610, Nov 8, 2018.

  1. pierre1610 macrumors regular

    Joined:
    Feb 3, 2009
    #1
    I have a CalDigit FASTA-6GU3 Plus card in slot 4, i've installed the 10Gbps firmware but am only able to get 400 MB/s from a NVMe 970 Pro in a USB 3.1 caddy which is capable of over 1000MB/s

    What gives?

    Slot-4
    Link width of card is x2
    Link speed 5.0 GT/s

    I also only have USB 3.0 Bus under system information

    OS is high sierra
     
  2. startergo macrumors 6502a

    startergo

    Joined:
    Sep 20, 2018
    #2
    Try this:
    https://github.com/pciutils/pciutils
    Use lspci -nnvv to see what is going on
     
  3. pierre1610 thread starter macrumors regular

    Joined:
    Feb 3, 2009
    #4
    Yes all other slots full

    is slot 4 slow then?

    Slot 1 GPU
    Slot 2 SSD blade
    Slot 3 SSD sataiii
     
  4. fhturner macrumors 6502

    fhturner

    Joined:
    Nov 7, 2007
    Location:
    Birmingham, AL & Atlanta, GA
    #5
    Slots 3 & 4 share an x4 PCIe link. If you have activity on that SATA III SSD in Slot 3 while doing your testing, OR if you're testing by transferring from that SATA SSD to the USB3 970 Pro, that shared bus would definitely impact your results.

    If that's not the case, I wonder if the card is a little bit hamstrung by the way it routes traffic to PCIe. The x2 link on a Mac Pro is going to practically max out around 750-800MB/s. If the card is dividing the eSATA and USB3 halves each onto their own x1 PCIe link, then each would be limited to about 375-400MB/s...which coincides w/ the cap you're hitting. That would seem strange for a card they're promoting as 10Gbps USB3.1, but not inconceivable...
     
  5. pierre1610 thread starter macrumors regular

    Joined:
    Feb 3, 2009
    #6
    Correction, i have a SSUBX in slot 3 which gets nearly 1GB/s
     
  6. fhturner macrumors 6502

    fhturner

    Joined:
    Nov 7, 2007
    Location:
    Birmingham, AL & Atlanta, GA
    #7
    Okay, gotcha. So your SSUBX and 970 Pro are going to be contending for that shared PCIe x4 bandwidth, which tops out at about 1500MB/s. So I'd say, unless one of them is completely idle, the other will not be able to max out its PCIe connection (which in the case of the 970 Pro, would be either x1 (~400MB/s) or x2 (~800MB/s) across your CalDigit card.

    What testing method are you using to get 400MB/s? Benchmark or transferring large files?
     
  7. bookemdano macrumors 65816

    Joined:
    Jul 29, 2011
    #8
    fhturner's explanation sounds spot on, and pretty easy to test. Remove the SSUBX you have in Slot 3 and rerun the benchmark. Or, if the SSUBX is your boot drive, take out the SATA drive in slot 2 and move the SSUBX there to re-test. I'd be curious to see the new numbers.
     
  8. fhturner macrumors 6502

    fhturner

    Joined:
    Nov 7, 2007
    Location:
    Birmingham, AL & Atlanta, GA
    #9
    Good thought. One thing to remember, too, is that you'll want to get that firmware updated to v138.0.0.0.0 or v140.0.0.0.0 so that your Slot 2 adapter w/ SSUBX will negotiate a PCIe 2.0 link @ 5GT/s. If you don't, it'll negotiate PCIe 1.1 @ 2.5GT/s.
     
  9. pierre1610 thread starter macrumors regular

    Joined:
    Feb 3, 2009
    #10
    I'm getting a x4 5.0GT/s link on my SSUBX

    Just moved my PCIe cards around.

    Slot1 - GPU
    Slot2 - SSUBX x4 5.0 GT/s
    Slot3 - FASTA-6GU3 x2 5.0GT/s
    Slot4 - Sata iii Angelbird SSD x2 5.0GT/s

    i still don't have USB 3.1 hub listed anywhere, only 3.0

    boot drive is now slot 4
     
  10. pierre1610 thread starter macrumors regular

    Joined:
    Feb 3, 2009
    #11
    Re-updated the firmware and now the system reads a 3.1 USB hub, still no faster though
     
  11. fhturner macrumors 6502

    fhturner

    Joined:
    Nov 7, 2007
    Location:
    Birmingham, AL & Atlanta, GA
    #12
     

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11 November 8, 2018