I have three RAM modules:

  • 1x 8GB (Brand1 - 3000Mhz)
  • 2x 4GB (Brand2 - 3000Mhz)

Here is my current configuration on ROG Crosshair VIII Hero motherboard:

  • A1: Empty
  • A2: 8GB
  • B1: Empty
  • B2: Empty

Can I populate A1 and B1 with my two 4GB RAM modules so it looks like this?

  • A1: 4GB
  • A2: 8GB
  • B1: 4GB
  • B2: Empty

This is not a memory configuration that is recommended by your manual.

The recommended configurations from the manual are:

enter image description here

However, motherboards can also adjust to non-recommended configurations.

I would counsel putting the two additional cards in A1 and B1, if there is any chance of them being used in dual channel. But you will just need to experiment, since this configuration isn't mentioned in the manual.


Ok, so my opinion differs from both harrymc and ramhound

Looking at the recommended memory patterns from the manual it appears that the map between the DIMM slot and the motherboard naming is going to be:

DIMM1 = A2 DIMM2 = B2 DIMM3 = A1 DIMM4 = B1

Based on this I would suggest a running the two 4GB modules in dual channel mode in DIMM1 and DIMM2, while the 8GB module is used in single channel mode in DIMM3.

A1: 8GB
A2: 4GB
B1: empty
B2: 4GB

This Intel application note may be helpful https://www.intel.com.au/content/www/au/en/support/articles/000005657/boards-and-kits.html

  • 1
    This is exactly what I had in mind and will try this asap.
    – OakDEV
    Nov 1 '20 at 15:35

Can I populate A1 and B1 with my two 4GB RAM modules so it looks like this?

You should fully populate the first channel and use B2 instead of B1 for the third module.

While depicted as a recommended configuration, the manual for the motherboard, indicates each channel supports different sizes of modules.

This means you will install the 4 GB modules in Channel A and 8 GB in Channel B (specifically B2)


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