Are there any limitations on PCI Express bandwidth..

Discussion in 'Mac Pro' started by ng7apoc, May 15, 2012.

  1. ng7apoc macrumors member

    Joined:
    Jul 29, 2010
    Location:
    UK
    #1
    ..When using all 4 Slots?

    What I mean is that if I were to purchase a refurb 2009/10 Mac Pro and in addition to the Video card I were to fill the remaining 3 slots with a 2 port USB 3.0 card, 2 port eSATA card and a SATA 3/6GBps RAID card would I see any bottleneck in bandwidth if all 3 cards were in full use?
     
  2. goMac macrumors 603

    Joined:
    Apr 15, 2004
    #2
    No.

    Individual slots have their own restrictions, but they're all independent.
     
  3. bax2003, May 16, 2012
    Last edited: May 16, 2012

    bax2003 macrumors 6502a

    bax2003

    Joined:
    Dec 25, 2011
    Location:
    Belgrade, Serbia
    #3
    Since 2008 Mac Pro (3.1), PCIe is v2.x.

    Specs for x1 bandwidth (V2.x) is 500 MB/s (5 Gb/s).
    Slots in Mac Pros are x16, x16, x4 and x4, so only limitation is bandwidth per slot.
     
  4. alphaod macrumors Core

    alphaod

    Joined:
    Feb 9, 2008
    Location:
    NYC
  5. COINcoin77 macrumors newbie

    Joined:
    Jul 16, 2010
    #5
    Correct me if I'm mistaken, but what I understood about the way PCIe slots are wired is as following:
    On the 2009/2010 models, 36 lanes are available. 16 wired for slot 1, 16 wired for slot 2, and the 4 remaining being wired to slot 3 and 4.

    So slots 3&4 cannot run both at full 4x bandwidth at the same time.
     
  6. GermanyChris macrumors 601

    GermanyChris

    Joined:
    Jul 3, 2011
    Location:
    Here
    #6
    This is correct I believe..
     

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