Operating system: Windows 10 Build 17134
Graphics card: Nvidia GTX 1080
(example: 2.80, 26d5a3625ed, blender2.8, 2018-11-29
When Using GPU Rendering Cycles crashes but when the CPU (Intel i7-6700) is disabled and GPU is enabled in "Cycles Compute Device" GPU rendering works but is very slow compared to just CPU rendering.
Exact steps for others to reproduce the error
Enable CPU in Cycles Compute Device
Enable GPU rendering