I have a late 2014 3.5 i5 27” iMac. We had to upgrade to 16gb from the standard 8gb. The machine runs 10.14.3 After three attempts, we finally received memory that worked. Well, after 2 hours of usage, the computer crashed. There were no normal kernel panic type messages. The computer froze, went black and restarted. The ram is from OWC. Can anyone help me? can anyone shine light on this for me? I started out by placing the 8gb sticks in the empty slots. I have removed the two original 4gb sticks.