Note that when the R10 was first released they only sold it with up to 64GB RAM options.  As an additional note, I do not believe that Dell has officially validated 128GB with zen 2 CPUs.  But keep in mind they don't normally validate hardware that they do not themselves sell.  The validated options you see are what was sold stock in the system.  
I know the manual says max is 64GB. But comments in Bios updates say that now 32GB sticks are supported.  "- Enhanced the maximum size of the slots to 32GB for XMP memory modules with the frequency 3400 MHz." ([URL] So I was wondering if that means max is now 64GB with 2x32GB sticks, or if anyone tried going over 64GB, with a 4x32 = 128 GB or 2x32 + 2x16 = 80 GB configuration? Where does the 64 GB limit come from? is it from BIOS? - Thanks!
Aurora R10, anyone try installing more RAM than 64GB?