Operating system: Windows 10
Graphics card: NVIdia Quadro M4000 (2x)
Broken: 2.80 all Versions since i started tests - 2.79 Dayli Builds (i think it came with support of rendering GPU and CPU together)
Worked: 2.79b official
Short description of error
Rendering with Cycles and both GPU's activated stopped Blender GUI without a message
Exact steps for others to reproduce the error
Just render a Scene with some Objects - GUI will disappear during rendering or shortly after the rendering. Rendering same Scene without GUI works fine and fast.