If you look at the R8 specification manual you will see 48 GB, 3 sticks is not a supported configuration. R8 manual    It is on page 13 of that PDF.
RAM: G.SKILL / DDR4 3200 (PC4 25600) / 3x16GB /  16-18-18-38 / Dual Channel Kit / Intel XMP 2.0 supportProc: I7-9700Current issue: When I have all 3 sticks plugged into the mobo I cannot enable intel XMP, and the ram speed defaults to 2133 @ 48gb. When going into BIOS the XMP drop down option is stuck on disabled and unclickable. When any combination of the 3 sticks is reduced to 2 (32gb) XMP works fine and ram speed comes up to 3200. So I’m struggling to find out how to enable XMP with 3 sticks plugged in.I'm seeing similar issues from previous posters "Aurora R9, error installing 64GB HyperX Fury DDR4 3200MHz RAM", but it seems crossmack can still get 48gb at 3200. Is my proc limiting this, something else?Any help would be appreciated!
Aurora R8, 48gb 3200 shows XMP locked on disabled