My macbookpro7,1 has had an RAM issue manifest a couple times since 2015. It is now rocking 16 GB of RAM and the lower RAM slot has stopped working twice now. This behavior was usually foreshadowed by the Mac not waking from sleep and running slower.

Both times, I seemed to be able to resuscitate the lower RAM slot by using a white eraser and rubbing it on the socket pins on the board and the RAM card itself. I’m pretty sure this issue has occurred, because I expose my macbookpro7,1 to temperatures below zero F daily during the winter for about 3 hours per day during my daily bike commute. I don’t give the Mac much time to equilibrate to room temperature when I arrive at my destinations, so I’m assuming some moisture may be condensing on the RAM connector pins. Seems I shouldn’t be so rough on my gear, but the eraser trick has brought it back.