MP 1,1-5,1 Upgrading RAM in 5.1 cMP

[macaddress]

32GB DIMMs are not supported by macOS, you need OpenCore to make it supported and the config is complex/manual.

When MacPro4,1 was designed back in 2008ish, the usual DIMM was 1GB, with 2GB options, 4GB DIMMs were insanely expensive. Back then made sense to have a 4th slot sharing the 3rd channel to have more memory installed, even if it was slower.

3Rx4 is an unusual type of DIMM that started to be supported with some blade servers with IvyBridgeV2 Processors, no Mac ever used one.

Ahh I see I just found it noticed they were booted into windows to get that result.

going to experiment with the 4rx4 and see how it reacts if i remove the 4 and 8 slot vs, the 2rx4.
(Note something is messed up with my system, i have no recovery due to following martins monterey guide)

Edit: Well how about that..? 4rx4 slots 1,2,3. - 5,6,7.
I assume I'm better off with the 2rx4? be a hot minute before I benchmark them

 

[macaddress]

MacPro5,1 was designed to work with dual rank DIMMs (2Rx4).

Just did testing, i need to break down more of blackmagics Braw more in depth so ignore that. but this was quick go.
Obviously 4Rx4 @800mhz 128 performed the worst. However, at 96gb 1066mhz is identical to 2Rx4.

 

[naniscola]

Hey folks,
a weird thing is going on: I set 6x 16 GB sticks (from one kind) in slots 1,2,3 / 5,6,7 and I got a red light on the board and one of them is not recognized (see picture). If I remove one, so there are only 5 left, everything is OK.
At fist I thought it was a faulty stick, but now I think that only 5 one can be fully accepted by the system, what is weird, because all posts here talk another language.
I'm on Monterey with OCLP 0.6.8.

Any hints how to get the full 96 GB instead of only 80 GB, which is also enough for me?
Cheeers from Frankfurt / Germany

 

[keksikuningas]

@naniscola have you tried different slot configurations to see if the slot you put the 6th stick into is faulty?

 

[naniscola]

@naniscola have you tried different slot configurations to see if the slot you put the 6th stick into is faulty?

Yes, all slots worked with the former 2gb and 4gb sticks. It is like I said: inserting the 6th stick gives an error, with 5 it’s fine, no matter which of the 6 you choose…

 

[keksikuningas]

Yes, all slots worked with the former 2gb and 4gb sticks. It is like I said: inserting the 6th stick gives an error, with 5 it’s fine, no matter which of the 6 you choose…

i'd try a NVVRAM reset if you haven't already done it

 

[naniscola]

i'd try a NVVRAM reset if you haven't already done it

Oh man, I did it before, you can tell. But now I ve done it 3x in a row and magically ALL the sticks were recognized!! Thank you very much!! So easy!
What was the downside of using all the 8 slots compared of using only 6? I have in mind using all 8 slows down the system, so you are better off with 6...