Eijkhout, Chow, and van de Geijn's "Introduction to High-Performance Scientific Computing, Chapter 1: Sequential Computer Architecture"
Read section 1.3 of Chapter 1 on pages 23 and 24 to learn about multi-core chips. These two pages give a summary of processor and chip trends to overcome the challenge of increasing performance and addressing the heat problem of a single core.
Click https://s3.amazonaws.com/saylordotorg-resources/wwwresources/site/textbookuploads/5345_scicompbook.pdf link to open resource.