Booting Macbook Pro 2012 from USB3

Discussion in 'macOS' started by Nikos.A, Oct 5, 2012.

  1. Nikos.A macrumors newbie

    Oct 5, 2012
    Hi all,
    I have recently bought a Macbook Pro 15"(mid 2012). I have a USB3 SSD drive that functions smoothly when connected to the mac. It runs at 200 MBytes/s read speed and 100mb/s write speed

    I recently installed lion on it to see if I can boot from it.

    The weird thing is that it works but after booting I checked system preferences and it's maximum data rate is 480 Mbits/s(USB 2). I thought that is really strange since when connected to my existing installation it works at full speed.

    It seems like an EFI issue to me.
    Anyone else with similar experience and/or a solution?
    Thank you
  2. chrfr macrumors 604

    Jul 11, 2009
    Are you running 10.7.5? My external USB 3.0 drive runs at full USB 3.0 speed, whether booted from it or not.
  3. Nikos.A thread starter macrumors newbie

    Oct 5, 2012
    Yes, 10.7.5
    I have also tried install ML, same behavior.. If you can boot from USB3 full speed then it is probably either incompatibility with the drive's firmware.

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