Only two USB 3 busses

Discussion in 'Mac mini' started by woodbine, Nov 30, 2012.

  1. macrumors regular

    Joined:
    Aug 8, 2010
    Location:
    Bath, UK
    #1
    I had a look at system report for my new MacMini 2012 and it says only two USB 3 ports and two USB 2 ports.
    Is this correct?
     
  2. macrumors G4

    flopticalcube

    Joined:
    Sep 7, 2006
    Location:
    In the velcro closure of America's Hat
    #2
    That is correct. Ivy Bridge CPUs have two USB 3 bus controllers built in and there is no other onboard bus controller on the logic board.
     
  3. macrumors 68000

    dmk1974

    Joined:
    Sep 16, 2008
    #3
    So 2 ports per bus then? You make it sound like only 2 of the 4 ports are at USB3 speed. Per Apple's site, all 4 ports are USB3.
     
  4. WLS
    macrumors 6502a

    Joined:
    Jul 10, 2008
    #4
    Is one bus controller for internal devices and the other for external? E.G are all 4 of the USB rear ports on the same bus?
     
  5. macrumors 68040

    Joined:
    Dec 17, 2009
    #5
    This is the standard setup for almost all computers. Any computer you buy, generally does not have a 1:1 BUS to port ratio, usually it is 1:2 bus to port (sometimes the ratio is even worse). Some laptops that have very few USB ports will have a 1:1 (if the only have 2), but even a friend's Fujitsu 12" laptop I used the other day had 3 USB ports and it was split with 1:1 on one USB port and 1:2 with the other two.
     
  6. macrumors 6502

    Joined:
    Nov 2, 2007
    #6
    So is there a way to know which ports are USB3? (via the system profiler porbably, correct?)

    This is sad, I thought it had four USB3 ports :(
     
  7. macrumors 68040

    Joined:
    Dec 17, 2009
    #7
    You misunderstand, they are ALL USB3, just that two will share USB3 bandwidth so if you plugged two high bandwidth items into two USB3 ports that share the same BUS, they might experience a slow down. Granted USB3 is faster than any mechanical hard drive can output (or two for that matter), so it would have to be something like hooking SSD's via a USB3 port that you might see this issue.

    EDIT: Think of it like 2 port USB hubs.
     
  8. macrumors 65816

    Joined:
    Jul 7, 2008
    #8
    It does. All the USB ports on the rear are 3.0.
     
  9. macrumors 603

    philipma1957

    Joined:
    Apr 13, 2010
    #9
    the mini is auto detect. plug in 4 usb3 devices restart the machine and all 4 ports will show usb3. plug in all 4 usb2 devices the mini will show 4 usb2. any combo it will show.

    Now as to the ability to run 4 usb3 devices at full speed at the same time most likely it can't do it. you could try to test it but not sure if it can be done that easy.
     
  10. rkahl, Nov 30, 2012
    Last edited: Nov 30, 2012

    macrumors 65816

    Joined:
    Jul 29, 2010
    #10
    What's the difference between USB 3 Hi-Speed and USB 3 SuperSpeed?
     
  11. macrumors 65816

    Joined:
    Jul 7, 2008
    #11
    There is no USB 3 hi-speed. Any reference to hi-speed is USB 2.
     
  12. macrumors 65816

    Joined:
    Jul 29, 2010
    #12
    My 2012 Mac Mini system report says that I have a USB 3.0 Hi-Speed Bus and a USB 3.0 SuperSpeed Bus. What's the difference?
     
  13. macrumors 65816

    Joined:
    Jul 7, 2008
    #13
    It's telling you that you have a USB 2 bus...I think.
     
  14. macrumors 65816

    Joined:
    Jul 29, 2010
    #14
    Sorry to sound dumb, but how do you know if you are plugging your external hard drive into a USB 2 or a USB 3 port?
     
  15. macrumors 65816

    Joined:
    Jul 7, 2008
    #15
    As far as I know, all the rear ports are USB 3. If you have a USB 2 device hooked up though, it might read as something lower than USB 3 super speed.
     
  16. macrumors 6502

    Joined:
    Nov 2, 2007
    #16
    Thanks for the explanation.
     

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