MacPro5,1 RAM configuration question

[M.Switch]

You should ask your question on the correct thread, people are testing 256 GB / 32GB DIMMs here:

https://forums.macrumors.com/threads/crazy-idea-32gb-ram-modules-in-a-cmp-anyone-tried-this.2046693/post-24597466

You will learn how to configure following the posts there.

Thank you @tsialex ... so much information to go through... heading there now.