How do I know which RAM stick to use with my laptop? I have a Dell Inspiron 15 N5050. I purchased a Dell ram stick like the one that Dell says works in it, but it doesn't work. My computer guy says it is probably a 10666 and I need a 10600. Since it doesn't say on the sticker, I don't know what it is for sure. However, he said that I can purchase a PNY ram stick like this one
and even though it is a 10666, he says PNY is "reverse compatible" and it will work. Does anyone know anything about this?