In the houdini.env file add the two variables below:

The first variable listed ensures that the GPU is used for OpenCL functions.
The second variable tells Houdini not to load the built-in CPU OpenCL driver that is shipped with Houdini.

HOUDINI_OCL_DEVICETYPE=GPU
HOUDINI_USE_HFS_OCL=0

Please refer here for where to find the houdini.env file.

You can also try renaming the OpenCL folder shipped with Houdini.
Go into the Houdini installation location and rename the OpenCL to OpenCL_OLD inside the bin folder.