I got a PowerMac G5 about a year ago, grabbed it to use as a secondary computer or to sell. It didn't come with a hard drive, but I finally grabbed a 250GB drive and threw it in there (after formatting to exFAT and making it a GPT). I've got OSX Yosemite installer from Transmac onto my USB drive. (PNY USB 3.0 64GB) I hold down ALT/Option and I get a screen that only shows a refresh icon and an arrow facing right. Does the hard drive need to be reformatted somehow? Can the G5 for some reason not install from a 3.0 Drive? Should I try loading the .dmg onto a DVD and installing that way?