Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce RTX 2080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 435.80
Broken: version: 2.81 (sub 13), branch: master, commit date: 2019-10-04 22:33, hash: rBab519b91b2c4
Short description of error
Understanding that not all cycles features are supported for this mode I still think it may be handy to point out that in cycles with GPU compute adding either of the following input node into the shader editor breaks the OptiX render in viewport. (Ambient Occlusion and Bevel)
Exact steps for others to reproduce the error
Preferences > Set system to OptiX > New > Set Engine to Cycles-Supported-GPU Compute > Open Shader Editor > Insert Ambient Occlusion or Bevel input node and do not connect > Move viewport.