Hello

There are two things to consider:

#1 Are both DIMM types the same? You cannot mix UDIMMs and RDIMMs.

#2 Memory is supposed to be installed in pairs, and in dual processor configurations both memory lanes(A, B) must have identical configurations. In a dual CPU configuration you should be installing a minimum of 4 DIMMs. Single DIMM configurations in A1/B1 are not intended for a production environment. That configuration is intended for troubleshooting.

If all of the DIMMs are the same type then your configuration should be:

1,2 - 8GB
4,5 - 2GB

Alternatively you could populate:

1,2,3 - 2GB
4,5 - 8GB

That will give you more memory, but may not perform as well as the first configuration. If the above configurations do not work then post more information about the specifications of the memory.

You may be able to get the memory to work in this configuration:

1,2,3 - 2GB
4 - 8GB

I'm quite certain that you will receive a warning with that configuration, but I'm uncertain if the DIMM would be disabled.

Thanks