Just wishing to confirm the old adage I'm holding to, is that for X memory on dual-cpu server, it better to have two X/2 sticks, as it enables each CPU to independently access said memory stick.

Was there any change with recent CPU's, or it still the same?

  • 3
    It depends entirely on the server/motherboard and CPU type/numbers - there's not one-size-fits-all these days, let us know the details and we'll try to help.
    – Chopper3
    Apr 4, 2011 at 12:22
  • 1
    For example, Dell R410 standard configuration, with 2 6-core CPUs (E5646 and higher).
    – SyRenity
    Apr 4, 2011 at 12:35
  • 1
    Consult with the server manufacturer or their agent. Apr 4, 2011 at 12:52
  • As both Chopper and John say, no one-size-fits-all and also to check with your Dell rep. Our Dell rep mentioned that they have worked it out with these R*10s as to what your best performance can be with memory, and these change for each server. You may have 2 different size sticks, or you may not, in the server with them being in particular slots.
    – Chadddada
    Apr 4, 2011 at 14:03

4 Answers 4


For that particular model the best performance is reached by using identical DIMMs in EVERY slot - although this isn't necessarily the cheapest or most future-proof option.


Dell R410 System Memory Configuration

Some recommendations:

  • Use registered DIMMS (RDIMM) - unregistered DIMMS are supported, but I wouldn't recommend them due to the small sizes
  • 8 slots are split in to 4 slots per processor with 3 channels per slot (2 DIMMS in channel 0, 1 DIMM for the other two)
  • In Advanced ECC mode, only 2 slots are available per processor (Channel 0), the other 2 are unused
  • Likewise, in Memory Mirroring mode, only 1 channel is used per process and 1/2 of the memory is not available due to mirroring
  • Optimizer Mode supports paired or odd numbers of DIMMS
  • Optimizer Mode also supports different sizes so long as the types match (RDIMM vs uDIMM)
  • The memory will run at the speed of the slowest DIMM installed

This will vary on each situation depending on the motherboard. Generally, or more recently rather, the sticks will interleave to form a dual/triple channel. Meaning on the side for CPU1 you'll have memory slots 1,3,5,7 and on the side for CPU2 you'll have memory slots 2,4,6,8.

  • This is clear of course, but in short you say that it still better to have 2 sticks instead of 1? :)
    – SyRenity
    Apr 4, 2011 at 12:48
  • No this is not clear, the board you could be speaking of could be from when there was no dual channel. In short though, I'd suggest using 2 sticks for this purpose.
    – Split71
    Apr 4, 2011 at 12:55

As Chopper3 stated, every dimm slot sould be populated for optimal performance on that particular motherboard. Using 2 dimms will not be optimal but would be somewhat better than 1 dimm (if 1 dimm is even a valid config)

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