Upgrade Memory on R710 (channel question)

I have a R710 server that I need to add more memory to.  It has 72 GB of memory now (6x8GB and 6x4GB) with 2 CPU sockets.  I read that it has 3 channels per CPU so I believe each channel has one 8GB module and 4GB module.

Can I upgrade the memory and put a single additional 8GB module in channel 1 for each cpu without adding memory to channel 2 and 3?

So channel 1 has

2x8GB + 1x4GB

while channel 2, and 3 have

1x8GB + 1x4GB

Would this be a valid memory configuration and that the server should boot no problem?