This is the guilty scene. After optimizing my geometry, I was able to render properly. The most memory used during the rendering process (I use task manager) is about 12 Gigs. If I add too much geometry, and my memory use reaches 90% - 100%, I get an error. This happens even before any tiles are rendered. I always thought CPU render used virtual memory.
What are your settings for the terrain mesh, are you using micropolygon displacement for example?
If so, you rarely need to have a dicing rate below 0.75. I will also note that if you’re using the 2.79 official release, diced geometry can consume a lot of RAM if it’s close to the camera.
I think @Ace_Dragon nailed it. This may be a problem with micro polygon displacement itself. I thought it would be symptomatic of what would happen if I had a complex scene with allot of geometry.