Different RAM capacities on different channels

[danwood82]

What are the rules when it comes to using different size (but otherwise identically specced) RAM modules?

I've got 4x 16GB Hynix modules, and 4x 8GB Hynix modules:
HMT31GR7CFR4C-PB
HMT42GR7MFR4C-PB

Both identical specification, and both officially supported by the Supermicro motherboard I intend to use them in.

The motherboard is a uni-processor Socket 2011, C602 chipset. It has 8 RAM slots, and quad memory channels.

Would there be any drawback to running the 16GB modules in the first bank of 4 slots, and the 8GB modules in the other 4?
I've read that mixing capacities within a duel/triple/quad bank will disable multi-channel support. Is there any such drawback to a configuration like I'm proposing?

 

[Jeggs101]

I believe as long as you keep them in the same channels you are OK. So the configuration layout should look like:

16GB - 8GB -16GB - 8GB CPU 8GB - 16GB - 8GB - 16GB

Good news is that it at least should work fine.

 

[danwood82]

Yep, that's the layout I figured. I had a feeling it should work fine, I'm just concerned there may be some hidden caveat in there somewhere.

Thanks for the confirmation.

 

[Chuckleb]

I quickly glanced at the SuperMicro manuals and Intel references.

Desktop Boards — Single and multi-channel memory modes

Ignore the desktop board comment, this should apply to server UP setups. You are looking at the Dual Channel with 4 DIMMS section I would say.

On Supermicro (http://www.supermicro.com/manuals/motherboard/C606_602/MNL-1284.pdf) page 2-10, they don't officially support mixed memory sizes, but doesn't hurt to try.

 

[danwood82]

It seems rather strange that they won't acknowledge the possibility of different sizes, even in separate banks, but they gladly advocate and support installing 6 matched DIMMS in a quad channel motherboard. I would have thought having quad interleaving on one bank and dual interleaving on the other would have higher potential for issues.

 

[nitrobass24]

It will work just fine....now weather there are performance penalties...you could test and let us know.