Does it matter which slot to use for SSD PCIe?

Discussion in 'Mac Pro' started by machenryr, Jun 9, 2019.

  1. machenryr macrumors 6502

    machenryr

    Joined:
    Jan 25, 2016
    #1
    I have my MacPro open and I thought I read somewhere that it matters which PCIe slot you use for the SSD blade, but I haven't been able to find this.
     
  2. zackkmac macrumors 6502a

    Joined:
    Jul 7, 2008
    Location:
    Tulsa
    #2
    Yes, it does. Here's the config:

    Slot 1 (16x) (best for GPU)

    Slot 2 (16x)

    Slot 3 (4x)

    Slot 4 (4x)

    Where Slot 1 is the bottom one (if you have the MP upright) and Slot 4 is towards the top. Use Slot 3 or 4 for best PCIe SSD performance.
     
  3. h9826790 macrumors G5

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #3
    Depends on your adaptor, and cMP firmware version, and if any card installed in other slots.
     
  4. machenryr thread starter macrumors 6502

    machenryr

    Joined:
    Jan 25, 2016
    #4
    LOL! Thanks! I just put it in slot 2. I had it in slot 4! LOL.
     
  5. h9826790 macrumors G5

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #5
    Slot 2 not necessary faster, but may be 50% slower if you use some simple adaptor with cMP firmware 0089.B00 or earlier.
     
  6. machenryr thread starter macrumors 6502

    machenryr

    Joined:
    Jan 25, 2016
  7. tsialex macrumors 601

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #7
    This was correct until BootROM MP51.0089.B00. After 138.0.0.0.0 all PCIe slots are 5GT/s. Slots 3 and 4 SHARE bandwidth, if you use two demanding cards you will have contention issues.
     
  8. machenryr thread starter macrumors 6502

    machenryr

    Joined:
    Jan 25, 2016
    #8
    What?? Lol. So now you’re telling me I was right to put it in slot 2?
     
  9. tsialex macrumors 601

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #9
    if you use two demanding cards with slots 3 and 4 you will have contention issues, if you have just one, won't be a problem.
     
  10. machenryr thread starter macrumors 6502

    machenryr

    Joined:
    Jan 25, 2016

Share This Page

9 June 9, 2019