Thank you, Geoff.
Then the next question is:
What maximum configuration can we use for maximum memory speed (1333 in our case) and what slots should we use? Dell R710 server manual states that for single and dual-rank modules "One memory module per channel supports up to 1333 MHz". So in Optimizer (Independent Channel) Mode would we be able to use 1333 speed for 6 modules at A1, A2, A3 & B1, B2, B3 in dual processor setup?