Ok, this is a strange one. I have DP 450 G4, and I recently bought 2 GB of RAM from Fry's for like $160 (the whole reason I got it was becuase it was such a great deal) Anyhow, I pop it all into machine, and what happens? My computer will not start up. So I pop in an old memory module and it's rolling. I try to find out what the deal is, and in Apple System Profile it says that my other memory slots are 'empty' even though they are full of RAM modules! These are PC133 SDRAM , 512 MB sticks, THEY SHOULD WORK!! I thought that perhaps a few of them were bad, but how can ALL of them be bunk?! Do you suppose this is why they were so cheap, and if so do you think I'll be able to return them?