How to switch to CPU Opencl
Before talking about the steps I would like to point out what you would gain from this, well it's not going to be as fast as a GPU Opencl (in my case intel 6800K vs GTX 1080) but definitely faster than the CPU without Opencl (almost double the speed). And it's going to use your system ram so you better have enough (anyway it's better than the gpu 8GB).
So let's start, it's as simple as:
1- Download the intel driver (OpenCL™ Runtime) Here..
2- Open Houdini.env (it's in: C:\Users\(user)\Documents\houdini\)
3- add the following line at the end without hashtag HOUDINI_OCL_DEVICETYPE=CPU
4- now if you open Houdini and checked in Help>about you will see that it's recognizing the CPU as the opencl device not the GPU.
5- Great that's it, you are done.