I am VERY new to Houdini (Indie, few days) but before learning the huge list of features I want to make sure my system is optimized for it

See my sig for complete system description.
The problem is that the “Use GPU to Assist Compositing” setting in Compositing/Cooking tab in Preferences is disabled i.e. grayed!

How is that possible when both my graphics cards are listed on Houdini supported graphics cards list?
I have tried to search this forum and the docs but so far failed.
Also I have tried but so far failed to find any tool that would show which GPU Houdini is actually using. I have tried to set the env variable HOUDINI_OCL_DEVICENUMBER but I would like to be sure that it uses the GTX 1080ti.
So can someone please help me to get answer to all/any of:
1. Tool to show Houdini GPU usage (at least GPU name/type)
2. Enable the “Use GPU to Assist Compositing”
3. Any other settings env varibales to set to get most out of my GPU(s)
Thank you very much

Antti

