Optimal RAM arrangement for Mac Pro 2013 (12-core, D500)

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YallaB Author

Level 1

4 points

Optimal RAM arrangement for Mac Pro 2013 (12-core, D500)

I have a Mac Pro 2013 (12-core, D500).

I have four RAM modules, each 16 GB:

2 × PC3-14900R-13-13-E2
2 × PC3-14900R-13-12-E2

What is the best way to arrange or install the RAM modules to get the best performance and stability?

this

Slot 1 → PC3-14900R-13-12-E2

Slot 2 → PC3-14900R-13-13-E2

Slot 3 → PC3-14900R-13-12-E2

Slot 4 → PC3-14900R-13-13-E2

or

Slot 1 → PC3-14900R-13-12-E2

Slot 2 → PC3-14900R-13-12-E2

Slot 3 → PC3-14900R-13-13-E2

Slot 4 → PC3-14900R-13-13-E2

Plz help

[Re-Titled by Moderator]

Original Title: MacPro 2013 Memory

Mac Pro, macOS 12.7

Posted on Nov 5, 2025 11:03 PM

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Answer 1

Nov 6, 2025 6:55 AM in response to YallaB

Best theoretical setup is matched pairs in adjacent slots. Conventional wisdom is the largest modules go in the lowest numbered slots, so I would be inclined to place the fastest (smaller number of states) in the lowest slots as well.

I don't know whether it will interleave beyond pairs, but whether it does or not, the difference will not be noticeable.

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Answer 2

kaz-k

Level 9

51,078 points

Nov 13, 2025 9:41 PM in response to YallaB

Hi,

It is said that for optimal performance in the 2013 Mac Pro (Cylinder), install matched pairs of ECC registered DIMMs(RDIMMs) in adjacent slots (A1/B1, A2/B2) for quad-channel operation, using the lowest numbered slots (A1, B1) for the first pair and A2/B2 for the second, ensuring all modules are the same speed and type (no heat sinks). This maximizes bandwidth, though differences between configurations might be slight unless heavily taxing the system.

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