Idk if this might help anybody but I originally had two 4Gb RAM boards (or whatever you call those little things) and no matter what I would do, couldn’t stop the old 15” MacBook from beeping and could’ve sworn they’re seated perfectly. Then stumbled upon this page, then was about to try and find something to stick in there because I don’t have styrene lying around, then realized, “Hey, do I really need both sticks of RAM? Nah! I just need the laptop to turn on.” So I left the bottom slot open and put one of my two sticks of RAM in the top slot and voila, bye bye beeps and this old MacBook is able to start up. I’m giving it to a friend who just needs it to play old DVDs and that’s it. Hooray!