Hello GlasgIT,

 

I see you are planning to add additional memory matching what you currently have.

 

Depending on what your memory mode in the BIOS -

 

If you have, or change to, Advanced ECC use:

A2, A3, A5, A6, B2, B3, B5, B6

 

If you have, or change to, Optimized mode you can use:

A1, A2, A3, A4, B1, B2, B3, B4

 

Memory guideline on Page 37-41 Modes described here also : https://dell.to/3jAAVcI

 

Please let me know if this helps.