[Paulienat]

I just installed 6x8gb Owc Ram Modules in the Mac Pro 2019 and I found out this:

I had 6 Apple 8gb original modules installed in slot 1-3-5-7-9-11 so, based on the knowledge that I had about the Hexa mode and how they share the channels I've left the original modules in their position and I just add the Owc modules in the free slots, 2-4-6-8-10-12.

When I turned on the Mac I had the orange light telling me there was a problem with Ram. So I checked again every module and reset. Same problem again.

Then I put all the modules in pairs so, Apple 1-2-3-4-5-6 and OWC 7-8-9-10-11-12. And it worked.

Apple tells you how to put different modules in the best sequence to optimize performances but they don't tell you how to integrate Apple-approved modules in the slots, except for the suggestion of not mixing different sizes and R-dimm with LR-Dimm