Mixing memory in R610

Hello,

I have read much about it and now I am a bit confused. I habe Herr a R610 Witz dual CPU configuration and 2x 4GB RAM, different 2x 4GB RAM and 2x 8GB RAM. So what is the right configuration in the server?

My config now is 4-empty-4-empty-8-empty-CPU-CPU-empty-8-empty-4-empty-4

This gives me an configuration error.

Thanks in advance!