Hi 1829116,
As Erik correctly mentioned since it’s a structural mechanics forum so you can post this question in the fluent forum. but for your answer, you can click on the show more option and select a “parallel setting” and find the option of the “solver gpgpus per machine” to choose. I have highlighted the option so you can see it. 
Regards,
Sampat
You are navigating away from the AIS Discovery experience