OK All,   This IS what happened and how it MUST be done and the Dell Tax. Intel says you CAN mix memory sizes of IDENTICAL memory BUT Dell Bios is not as friendly as it could be. It only works this way! CPU Left to Right  32 32 16 16 (aka slots 1>4) when you use CPU-Z (A tool that people who TS use) Double Tax is the speed that is already downclocked to 4400 goes to 3600... Intel FLEX mode has been around for DECADES... Dell manual could be more forth coming on mixing sizes in pairs, etc.     [IMAGE]Dell Tax    
I have all the same memory Sticks (Made by Hynix)  and slots doesn't matter other than I can ONLY get 3 to work at the same time. I have 3 16G sticks and 1 32G sticks.  They are ALL the required DDR5 UDIMMs 4800. If I install 4 the system will NOT boot and blinks memory errors. Question :  If I bought another 32G would it work?  It doesnt care which slots the 32G goes in or matching channels. I updated the BIOS too... Any thoughts? Thanks John
Aurora R13, can't run 4 DDR5 UDIMMS of different sizes