hello, mac-forums.This is my very first post ever,in any kind of forum,so please be considerate of this.Im also new to mac as of this month.anyways just bought a 2 gb ddr2 667mhz pc5300 ram card,it works great in either slot...i was previously running a 1gb of the same specs from a old lenovo machine i had around.The 1gb also runs fine in either slot...when i combine them i just get a black screen w/ the front (sleep) light on. Im sure their seated correctly. my machine should read 4 gb and adress 3gb? I think it may have to do with the sticks not matching.i also tried a lynx 1gb pc6400 from my dell inspiron w/ the same results.Thanks so much for all your time, once again sorry if im unclear, im new at this.Any advice would be much appreciated!