nMP memory in a cMP

[cdf]

I’m interested in upgrading the memory in my 2009 4,1 Mac Pro, and I’d be doing this quite inexpensively with memory pulled from a 6,1. There is evidence that says that this works (see the links below). But there is only one explicit mention of the modules: Micron PC3-14900E-13-13-D1. I’d be upgrading with Hynix PC3-14900E-13-12-D1. Note the different JEDEC SPD numbers: 13 vs. 12.

Does anybody know what the difference is between these two nMP modules? Is there reason to believe that the 13 would work in a cMP but not 12? Any help is greatly appreciated.

https://forums.macrumors.com/threads/buy-newer-1866-ram-for-classic-mac-pro.1915625

https://forums.macrumors.com/threads/ram-for-mac-pro-5-1.1863465

https://discussions.apple.com/thread/7206887

 

[h9826790]

If you put them in cMP, both stick will down clock to 1066 CL7 or 1333 CL9, none of them can maintain CL 13.

Anyway, the 2nd number is not the latency, you can go to the manufacture's website and get the fact sheet to decode.

 

[cdf]

In case anybody is wondering, the Hynix PC3-14900E-13-12-D1 nMP memory indeed works in a 4,1. I have 6 installed. I also have some Micron PC3-14900E-13-13-D1 memory, and that works too (but that had been reported before). Combining the two also works.

Thus, with many nMPs being upgraded, their stock memory can be obtained, often inexpensively, and serve as a modest, yet effective upgrade in a cMP.