MacMost Q&A Forum • View All Forum Questions • Ask a Question 4/19/177:54 pm How Do I Factory Reset an iMac G5? How do I factory reset an iMac G5? —– ILAN Comments: One Response to “How Do I Factory Reset an iMac G5?” Gary Rosenzweig 2 years ago For something that old you will need the system DVDs that came with it, or one of the old upgrade discs, like the Snow Leopard update disc, assuming that it is compatible with even Snow Leopard. You need to boot from the DVD (hold down C while restarting) and then use the options presented to erase the drive and re-install OS X. Comments Closed.