Mac pro won't startup when external drives are "on".

Discussion in 'Mac Pro' started by iHanuka, May 16, 2018.

  1. iHanuka macrumors newbie


    May 16, 2018
    I am using a mac pro 2008 with a Mercury Accelsior E2 PCI express with an internal Solid State Drive on the card and 2 external SSD drives.
    I am using Mac Os X El Capitan and it's installed on the SSD that is physically on the card. and this is the startup disk.
    When the external drives are "OFF" the computer starts up just fun.
    But, When the 2 external drives are "on" the computer won't startup, as if it can't find the startup disk.
    So I can't leave them on.
    Any ideas?
  2. adam9c1 macrumors 68000


    May 2, 2012
    Totally wipe the external drives (using a different computer). Then plug in to your tower.
  3. crjackson2134 macrumors 601


    Mar 6, 2013
    Charlotte, NC
    This happens sometimes with PCIe drives. They lose their startup disk settings after a PRAM and/or SMC reset. Sometimes after an extended power loss too.

    Try going into your settings > Startup Disk > Select the PCIe drive you want.

    That may or may not fix your problem. It does for me...

    On first boot with ALL external drives attached and powered on, try holding the option key as you power it on. Continue to hold it down from the time you hit the power button, until you see all the boot options. You should be able to select your desired drive and boot. If that works, then selecting the same drive from the startup drive settings outlined above should fix your problem..

    Hope this is the issue, and fixes your problem. Good luck.

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