Let Jon Masters, Computer Architect at Red Hat, help you understand just exactly how Spectre and Meltdown work. While he had to plow through his 90 slide presentation on stage in 45 minutes, he has been nice enough to give us direct access online. However you can click through those as slow as fast as you wish. The PDF entitled, Exploiting modern microarchitectures: Meltdown, Spectre, and other attacks, is available here.