I ended up replacing the dual E5-2697v4 with dual E5-2696v4 and now all my ram slots work So I think those 2697 cpu's must have had a problem or something. It is odd for them to BOTH be bad in the same way, but they were both used and from the same seller so who knows For now i just have A1-A6 and B1-B6 populated and it runs at full 2400 speed
Bought a R730xd with dual E5-v3 cpus (E5-2630v3). Everything worked without problems Upgraded to dual E5-v4 cpus (E5-2697v4) without changing anything else. Bios, and all firmware is up to date using idrac to update. Bios version 2.16.0 Now only ram in slots to the left of the CPU show up at all. Slots to the right of the bios show errors when posting that the memory in slot XX had a recoverable training error and to try reseating the dimms. For example, install eight 8GB sticks of 1Rx8 Ram following manual  in A1,A2,A3,A4,B1,B2,B3,B4. A1,A2,B1,B2 doesnt show up, but does in A3,A4,B3,B4. Bios only reports 32GB of ram. Lifesycle controller -> system assessment only shows ram in A3,A4,B3,B4 All of the slots to the left of the CPU show up, all of the slots to the right of the cpu do not. If i go back to the E5-v3 cpus, everything works normal. all ram in all slots show up. If I try single E5-v4 cpu configuration, for both cpus, same issue. So it is not the mobo, the ram, or the cpu at the hardware level that is causing the problem (to my knowledge) I also tried entirely different 1Rx4 ram and same issue.    Also, The ram only runs at 1866 speed, despite all the dimms being 2400T speed and exactly the same (all 1Rx8 and all same mfg) Cant figure this one out.   The memory configuration is set to optimizer mode, so it isnt one of the weird modes where only half the ram shows up to the OS.   Here is a photo of what i mean on left of the cpu. All sticks in this image show up properly, but any sticks put in the slots occupied by blanks do not show up. Even if the memory configuration is correct according to the manual  [IMAGE] Please let me know if I can provide any other info. Thanks! 
R730xd with E5-v4 cpu only sees ram in slots to the left of CPU