Hello. You are getting the complaint that  memory configuration not optimal because the memory channels are not balanced. Refer to the diagrammatic illustration below: [IMAGE] By balancing the channels we mean that the memory on slots A1, A4 &A7 have to match memory on slots A2 ,A5 &A8 and slots A3, A6 &A9. The same applies to slots on channels on CPU2, moreover  A1, A4 &A7 have to match B1, B4 &B7 and so forth. Therefore, you are correct to populate 8X16GB modules on Slots A1, A4, A2, A5 and B1, B4, B2 &B5 for optimal configuration with Memory Mode set to Optimal. Ensure that your BIOS is up to date
Hi forum, I just put 8 16 GB modules in my R710 (2 CPU). That works after hitting F1 but it complains that the configuration is not optimal. DIMMs are in A1, A2, A3, A4 and B1, B2, B3, B4. Memory Mode is set to Optimal. The RAM is 1600 MHz, dual rank. I assume it has to be A1, A4, A2, A5 + B1, B4, B2, B5. Am I right? Should the Memory Mode stay or better Advanced ECC? Thank you! eine-delle 
R710 with 8x 16 GB dual rank. How to populate?