I purchased a used N64 from a pretty well known retro game store online that came with an aftermarket expansion. To my dismay it would load games, but freeze up after 5-20 seconds of play. I was hoping it wasn't the console itself, so after reading some troubleshooting tips I ordered one of the official Nintendo expansion packs since the console didn't come with the original jumper pack. Plugged this in and it worked like a charm. I ordered a 2nd one in the event the RAM goes bad down the road as these original expansion packs are starting to become scarce.