Thanks. We already have all of the DIMMs installed as laid out in my second scenario (C&D are filled completely, A&B have 4 DIMM's each). I was just wondering if I should even them out for better performance.

Yes

In a dual-processor configuration, the memory configuration for each processor must be identical. For example, if you populate socket A1 for processor 1, then you must populate socket B1 for processor 2.

Hello kevin79

Should I put an equal amount of RAM in the slots for each CPU? (Fill A1-A8, B1-B8, C1-C8, D1-D8) If I fill all of the ones up top first (C1-C12 and D1-D12), will the other 2 CPU's share that memory?

The lane population must be identical across the CPUs. If you have 4 DIMMs for CPU 1 then you must have 4 DIMMs in CPU 2, 3, and 4.

You can refer to page 46 of the user's guide on population rules: http://ftp.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_poweredge/poweredge-r820_Owner%27s%20Manual_en-us.pdf

I need to know what type of DIMMs you currently have before I can say for sure that you can add more. If you have UDIMMs or quad rank DIMMs then you are at maximum population. If you have anything else then you can add more DIMMs.

Thanks

Thanks. We already have all of the DIMMs installed as laid out in my second scenario (C&D are filled completely, A&B have 4 DIMM's each). I was just wondering if I should even them out for better performance.