I found this recently, it seemed interesting. I haven't read through the whole thing but it seems like a good explanaition of how modern graphics processing works. It's aimed at "graphics programmers that know a modern 3D API (at least OpenGL 2.0+ or D3D9+)" so I thought other folks here might like to read and comment.
https://fgiesen.wordpress.com/2011/07/09/a-trip-through-the-graphics-pipeline-2011-index/ (https://fgiesen.wordpress.com/2011/07/09/a-trip-through-the-graphics-pipeline-2011-index/)