We have a G4 Mac Mini, circa 2005, running Mac OS X 10.4 Tiger, and we want to upgrade to 10.5 Leopard. We have a Leopard install disk, but the optical drive in this mini is broken. So we transferred the install disk image to a USB HDD, but now we can't figure out how to boot off it.

From what I've read in Mac forums, some PPC Macs, including some G4's, have been able to boot from USB, even though it sounds like this wasn't officially supported, and it may well depend on the specific model of USB drive and Mac. My Mac says CPU is "PowerPC G4 (1.2)" and Boot ROM is "4.8.9f4". I was hoping I might just find somebody here who had that same Mac Mini and find out if they could make it work. I'd especially like to know any specifics about the USB drive they found success with. Any insights at all would be appreciated. Thanks.


On a PPC Mac such as your G4 Mac Mini, you have to use a Firewire drive. USB booting wasn't really supported before the Intel Macs. You can use a Firewire optical external drive, a Firewire harddrive that has the OS Installer restored to it, put the Mac mini into Target Disk mode and install OS X on a Mac with a working optical drive, or you could even use NetInstall on a MacOS X Server machine.

  • I'm not in a position to test it, but according to this tuaw.com/2006/10/25/… PowerPC Macs can boot from USB. Granted, not all can though, as explained here macosxhints.com/article.php?story=20060301112336384 Jan 15 '10 at 18:56
  • Much thanks for the pointers. I only have the one Mac and no firewire drives, so I'm hoping for a USB solution, though maybe that's unlikely. Alas I haven't had much luck with the tips in Steve's links, so I think either it can't be done on my system, or it can only be done with certain USB drive models. Still hoping somebody has had success with my Mac model and could share what USB drive they used.
    – David
    Jan 15 '10 at 20:30
  • 1
    I finally got my hands on an Firewire hard drive and this works like a charm. (FWIW I'm using a 256GB Iomega Firewire400/800/USB2.0 Mac edition, Model RPHD-TG.) Restored the image to a partition on the drive, rebooted with option key held down, and it was simple point and click from there out. There may be a magic USB drive out there, but I think generally tegbains is right, at least in my case.
    – David
    Jan 16 '10 at 6:46

I hold down command, select the drive to boot from, and it just works. I have done this for both USB sticks and hard drives on many different types of macs.

If this does not work for you, perhaps you did not properly format the drive to make it bootable.

  • 2
    BTW, it's ALT, not COMMAND which starts the boot manager. Jan 15 '10 at 18:59

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