R610 Memory upgrading with mixed memory

Hello, 

I have been searching for answer with mixed memory upgrading and I have found 2 answers what collide to each other. We want to upgrade our 4x r610 with 2 CPU's servers and have some load balancing. We also want to upgrade our r620. 

Configuration at this moment, (all same speeds an banks etc)

R610 # 1 12 * 16 gb 192 gb
R610 # 2 12 * 16 gb 192 gb
R610 # 3 12 *   8 gb   96 gb
R610 # 4 12 *   8 gb   96 gb

R620 # 5   6 * 16 gb

We have bought 6x 16 gb to ad to the R620. This wont give any problem I think. 

But we want to load balance our 610 servers. Our idea was to configure them like this 6 * 16 and 6 * 8. So that the Total ram is equilized and should have same load on. As the #1 and # 2 are quite busy now. 

The configuration I wanted to use was as follows:

Now I have found 2 answers who collide to each other. 

This LINK here tells me that the only problem with mixing memory is that you will not be able to populate the third channel. It will make slots A3,A6 - B3,B6 unusable.

But this LINK tells me that is OK to mix memory and third channel can be used. Look at the last picture. They have mixed 4 and 2 gb and the texts don't mention anything about the above statement.

So the question is, is possible  to make the total ram equal each other of the R610. Or is this not smart and the configuration we have set-up now is the best option we can get, also performance wise. 

Any advise is welcome.

Thanks in advance.