MP 1,1-5,1 Installing 128GB of RAM

sk0n3_jp

macrumors newbie
Original poster
Feb 19, 2019
16
6
Irvine
Hi guys, I'm not sure if this kind of a thread already exists but I couldn't seem to find anything so here I go. I currently have 128GB of RAM for my Mac Pro 4,1 -> 5,1. I seem to have some kind of a problem on my dimm slots and I don't know what is it, so here's the deal.

when I install all 8 dimm slots several of my dimm slots are not recognized. some of it seem to go away when I reset the ram stick others are not lucky... * unrecognized slots denoted with "/"

1 2 / / 5 6 7 8 or
/ 2 / / 5 6 7 8

However, I read up on everymac that the max supported ram for this machine was 96GB so I try installing on double triple channel. *empty slots denoted with "[]"

/ 2 / [] 5 6 7 [] or

1 2 / / 5 6 7 8

I've tried other configurations too slots overall at this I assumed that both 3 & 4 were dead but... this configuration worked

[] 2 [] 4 [] 5 6 7 8

The Mac Pro originally came with 4, 8GB dimms in this configuration:

1 2 3 4 [] [] [] []

However, after some point in time I noticed that my ram capacity decreased to 8GB on which I moved the dimms to this configuration:

1 2 [] [] 5 6 [] []

I can't seem to grasp what the problem may be. Sorry for the lengthy posted. And much thanks to your help :):)
 

sk0n3_jp

macrumors newbie
Original poster
Feb 19, 2019
16
6
Irvine
wrong or mixed dimms
I bought it as a 128GB, 16GB x 8 dimms as one batch from the same vender and the labels also match.
speeds are also the compatible, as I have reconfirmed them on the ram manufacturer's website, the physical card, and the apple support web page.
 

Snow Tiger

macrumors 6502a
Dec 18, 2019
854
567
I bought it as a 128GB, 16GB x 8 dimms as one batch from the same vender and the labels also match.
speeds are also the compatible, as I have reconfirmed them on the ram manufacturer's website, the physical card, and the apple support web page.
If you want to activate tri channel memory optimization with the maximum amount of memory , install six 16GB matching modules in the following slots : 1,2,3,5,6,7 .

Are you getting any red LEDs on your CPU Tray ? Those modules are failing in those slots . Try swapping the modules in those slots with red LEDs into slots that have no red LEDs. Its a bit of a juggling act , but you can often get everything to handshake if you're stubborn enough . If this doesn't work , then one or more of your modules really have failed .
 

MIKX

macrumors 68000
Dec 16, 2004
1,725
638
Aussie in Japan
sk0n3_jp

Assuming that ALL your RAM is from the same manufacturer, remove one module, take a clear photo of the label on the RAM module & post that photo here.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.