I have several macs that I have tried it on, the only one that will not accept it is my 800MHz 17" imac. I even tried to do the open firmware to no avail. I hope someone finds a way of doing it. I maxed-out my RAM on all machines first, so that took some time. The lowest is a 533MHz. I do suggest having a little more than half of your hard drive available before trying it. I learned the hard way on the 533MHz. I had a 40Gb then went to an 80GB.