R710 - Memory error/upgrade

All,

At the moment I have received 2 dell R710's build same week.
Now in server 1 I have 2 CPU's and want to update from 8 to 16Gb.

Memory mode is Advanced ECC or Mirrored.
So I stack the following:

4x Samsung M391B5673EH1 in slots A2-A3-A5-A6 
4x Samsung M393B5673EH1 in slots B2-B3-B5-B6

When booting the server no screen and following error in IDRAC;

Can someone help me what I am doing wrong?

Thanks