I found that I ended up having two problems with the Mac se/30, one was all the simms were different. When I ordered and got a set of simms that had the same speed that fixed one problem. The other problem was a bad boot disk that had a error one it but was not showing expect to stop booting. I had bought the rommnater from messofwires that has os7.1 on it and after I replaced the simms it would boot.