Compiling Blender with Optix on Ubuntu I followed that instruction add optix device for installing Nvidia driver, Optix and compiling Blender. No errors but also no Optix in Blender. Here is debug:


  CPU flags:
    AVX        : TrueAVX2       : True
    AVX        : True
    SSE4.1     : True
    SSE3       : True
    SSE2       : True
    BVH layout : BVH8
    Split      : False
  CUDA flags:
    Adaptive Compile : False
  OptiX flags:
    CUDA streams : 1
  OpenCL flags:
    Device type    : ALL
    Debug          : False
    Memory limit   : 0  


My system is based on amd Ryzen 2700x, Nvidia rtx 2080, running 19.04 with Nvidia 435.17, Optix v.7
Really not sure what to think about, where to look for errors.

I don't know if my CPU is the problem and the question is which directory should I put the OptixSdk in for compiling with Blender?
The cmake patch for OptiX searches for the SDK in the following directories

SET(_optix_SEARCH_DIRS
  ${OPTIX_ROOT_DIR}
  "$ENV{PROGRAMDATA}/NVIDIA Corporation/OptiX SDK 7.0.0"
  /usr/local
  /sw # Fink
  /opt/local # DarwinPorts
) 


Where OPTIX_ROOT_DIR can either be an environment variable or the path explicitly set by using -DOPTIX_ROOT_DIR when using cmake. $ENV{PROGRAMDATA} is the environment variable to the ProgramData directory, which would usually be C:\ProgramData.

So your OptiX SDK has to be in either one of these paths (although on Windows it should be C:\ProgramData\NVIDIA Corporation\OptiX SDK 7.0.0) and you would have to create a release build. Alternatively you can configure the cmake setup yourself and specify that you want to use Optix (unless you do a release build) using WITH_CYCLES_DEVICE_OPTIX=ON and the path to the SDK OPTIX_ROOT_DIR=/path/to/NVIDIA-OptiX-SDK-7.x.x-xxx. This is described here, but can also be seen in the code of the patch. How to set these cmake variables is documented in Compile Blender with CMake for building on Linux in the section for Editing CMake Parameter which is pretty much the same on Windows.