I've never had a problem with RAM and had no idea they had gotten so specific now. With all of my custom machines (I've had one running basically at all times since I was 14) it always seemed to just be a matter of getting the right socket, DDR type, & speed, and it has always just seemed to work. I've never had a compatibility problem.
I guess I'm just out off practice or got complacent and thought I could just kinda piece meal it together without following an explicit list. Frustrating as hell though.