Just bumped into an odd problem with my MacPro4,1 (2009/Nehalem) wherein I cannot boot from USB bootable disks. My various disks are recognized from System Preferences -> Startup Disk, however they will not show up in the EFI Startup Manager at system boot.

I thought that the 2009 model was able to boot from USB disks and of course still FireWire at that time, however now I'm beginning to question my sanity. Another of my Mac Pros (2010 model) works just fine with my bootable USBs and so I'm not finding a clear answer as to this 2009 model is able to or if simply these boot disks were not formatted properly (partition type) for this model.

  • Every Mac Intel should be able to boot from USB. – Matthieu Riegler Jul 12 '13 at 9:01
  • But must it be formatted with GUID Partition Table? – GEdgar Jul 12 '13 at 21:05
  • Yeah, well I thought that as well + the GUID item. So I'm at a loss as to what is precluding boot. Hrm. – ylluminate Jul 12 '13 at 21:50

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