I tried the memory in the listed solution of :

A1, A2, B1 &B2 =16 GB

A5, A6, B5, &B6 = 8 GB

and still received the "Memory not optimal" error.  Thinking that it could be an issue with 2 different speeds of memory, I tried only installing the 16GB modules as:

A1, A2, B1, B2 and still received the "Memory not optimal" error.

Thanks again.  I greatly appreciate the assistance!

Thanks for the info Robert!  I will try to see if that configuration works.

Where can I find more information about the "Channels" of memory as they relate to my Dell server.  I have more experience with HP (boooo) and find it more difficult to understand the Dell layout.

Thanks for the info Robert,

I'm a little confused, you stated that A1, A2, B1 &B2 =16 GB & A5, A6, B5, &B6 = 8 GB would provide optimal memory configuration, but when I installed it in this configuration it was not optimal.

Also, it was my understanding that the mixed memory speeds would operate at the slowest common frequency, not the fastest frequency.

With the configuration of  A1, A2, B1 &B2 =16 GB & A5, A6, B5, &B6 = 8 GB the DIMMS would create an imbalance across channels C&D correct?

In your latest post, you stated that memory channels must have identical DIMMS in each channel,  does that mean that Channel A,B,C,D must be populated or can channel A,B be populated only?

Robert,

Thanks for the update.

I am currently on BIOS 1.5.2

I did attempt to only populate A1, A2, B1 &B2 with 16GB DIMM, I still received the "Memory not optimal error"

Thanks for the info Robert.  Do you know if I can accomplish the same updates by using the Dell  Deployment Toolkit CD?

Thanks Robert, I will check that out.

I was looking at downloads.dell.com/.../poweredge-r715_reference%20guide3_zh-cn.pdf

And the common theme that I see is that in almost all configurations, A1,A2,A3,A4 B1,B2,B3,B4 are always fully populated.  I do not see the configuration that you suggested of  A1, A2, B1 &B2 =16 GB & A5, A6, B5, &B6 = 8 GB listed

Robert,

I upgraded the BIOS, Lifecycle Controller, iDRAC and tried the following configuration of memory:

A1,A2, B1,B2 X 16GB

and still received the not optimal error.  To ensure that the issue was not related to the 16GB DIMMS, I installed the 8GB DIMMS in the following :

A1,A2, B1,B2 X 8GB

I still received the not optimal error.

I noticed the first time that I booted into the (non updated version) Lifecycle controller, Error messages (these before I had made any changes to the memory configuration) *Please see attached Photo*

After the updates were performed, I did not notice this error when I entered the Life cycle Controller.

I installed the following configuration:

A1,A2,A3,A4 B1,B2,B3,B4 - 8GB

added

A5,A6,A7,A8 B5,B6,B7,B8 - 4GB DIMMs

System was satisfied with the memory.  Is it possible that the documentation is incorrect and all channels must be populated?  

I found this document downloads.dell.com/.../poweredge-r715_reference%20guide3_zh-cn.pdf

which states that the max speed for Quad Ranked RDIMM low voltage speed is 1333.

Could this be the reason for the error?