Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
you'll have to use some pressure. make sure the clips on the side are "open".

Thanks so much for the advice! I was worried to push too hard, but it did need a surprising amount of pressure. Hopefully, I didn't mess up the RAM with my abortive attempts to slide it in smoothly!
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.