Hello, its been a long time since I posted, I just picked up a Power Mac G5 (Late 2005) and it currently has 512mb ram The memory installed is non ECC it is PC2 4200u-444 of course 2 256 sticks. I got my hands on 4 matching 1GB sticks of crucial PC2-4200R-444 ECC memory. Of course it dont work or I wouldnt be posting. I am getting 3 beeps followed by the fans blowing full blast. The code shows that no available RAM or something along those lines. According to Crucial the G5 does accept ECC memory I did not mix non-ECC and ECC so I am at a loss to what the problem is. The memory came from a working Dell server so I know its good. Is it just not compatible or am I missing something? Any help is appreciated.