MP 1,1-5,1 Mac Pro (Mid 2012) only recognize 24GB of 32GB RAM

[iku_nomac]

Hi,
I didn't find a solution in other thread concerning my issue. I bought 4 x 8GB RAM 1066Mhz DDR3 modules. The Mac is running 3.2 GHz Quad-Core Intel Xeon CPU, (Mojave OS)
It only recognize 24GB of 32GB RAM. I tried to change slots and RAM pieces. There is always a red indicator light at last taken RAM slot but not always on the same bank or with the same RAM stick.

Seems like RAM are ok and also the slots. I tried different variants.

Is this a firmware issue?

 

[AdiPlayZ]

Try resetting the pram

 

[iku_nomac]

Try resetting the pram

This answer isn't helpful. If you read what for is the PRAM reset you will see that this wouldn't fix my issue.
Perhaps a SMC reset would be a way but not really sure. If you read about its more a rumor if you got no more advice left.

 

[chrfr]

This answer isn't helpful. If you read what for is the PRAM reset you will see that this wouldn't fix my issue.
Perhaps a SMC reset would be a way but not really sure. If you read about its more a rumor if you got no more advice left.

Try it anyway. It’s non-destructive.
Since you asked about firmware, it’d be useful to know which version you’d computer is running.

 

[AdiPlayZ]

This answer isn't helpful. If you read what for is the PRAM reset you will see that this wouldn't fix my issue.
Perhaps a SMC reset would be a way but not really sure. If you read about its more a rumor if you got no more advice left.

Well that's the only thing I knew (Except SMU reset). I new to the Mac world being the late 2005 Power Mac G5 Quad as my first Macintosh ¯\_(ツ)_/¯.

 

[Roman78]

What CPU is installed? Is it a W3565? Than it is normal, it only supports 24GB of RAM.

Source: https://ark.intel.com/content/www/u...65-8m-cache-3-20-ghz-4-80-gt-s-intel-qpi.html and http://www.cpu-world.com/CPUs/Xeon/Intel-Xeon W3565 - AT80601002727AB (BX80601W3565).html

You have to upgrade to a E or X version of the Xeon. And if you do, just go for a 6-Core, like the X5680

 

[h9826790]

What CPU is installed? Is it a W3565? Than it is normal, it only supports 24GB of RAM.

Source: https://ark.intel.com/content/www/u...65-8m-cache-3-20-ghz-4-80-gt-s-intel-qpi.html and http://www.cpu-world.com/CPUs/Xeon/Intel-Xeon W3565 - AT80601002727AB (BX80601W3565).html

You have to upgrade to a E or X version of the Xeon. And if you do, just go for a 6-Core, like the X5680

That max memory limit is wrong (or may be more precise, not updated).

It’s a well known fact that those W3xxx CPU can run 3x16+8 = 56GB RAM on the cMP.

Same as my W3520 and W3690, Intel said 24GB max, but I can run 4x8GB, 3x16GB, and 3x16+8GB without any issue.

OP's issue isn't really the CPU spec related. You may call that config is not supported, but definitely can work on cMP.

 

[h9826790]

This answer isn't helpful. If you read what for is the PRAM reset you will see that this wouldn't fix my issue.
Perhaps a SMC reset would be a way but not really sure. If you read about its more a rumor if you got no more advice left.

If you ever read this forum's threads about memory upgrade. Then you may realise there are lots of case that NVRAM reset does fix memory their issues.

Even that may not work for your case, however, NVRAM reset can fix memory issue on cMP is a fact.

Also, for your info, memory config is stored in the NVRAM private stream. Even that can't be cleared by NVRAM reset. However, NVRAM reset may force the cMP to re-detect the memory config. This may be the reason why NVRAM reset can fix the very popular "wrong memory clock speed" issue (after memory upgrade from 1066MHz to 1333MHz)

There is always a red indicator light at last taken RAM slot

Also, sorry for my poor English, may I know what this actually means? What is the "last taken RAM slot"?

Is this a firmware issue?

Possible, but very rare. As I said, the memory config is stored in the firmware. Therefore, memory issue can be firmware related.

Anyway, what's the full spec of your DIMM? Any photo of the label? Wrong memory spec can also be a problem.

 

[Macschrauber]

Important in this case:
3 nvram resets in a row are needed to re read ram details.

If firmware is the case a flash with generic firmware for test sake can give an answer. If generic firmware is ok than it needs to get rebuilded. In a very basic way I can do that, but much better tsiAlex.

Also: are these Rams 2rx4 or 4rx4 types?

 

[Roman78]

That max memory limit is wrong (or may be more precise, not updated).

It’s a well known fact that those W3xxx CPU can run 3x16+8 = 56GB RAM on the cMP.

Same as my W3520 and W3690, Intel said 24GB max, but I can run 4x8GB, 3x16GB, and 3x16+8GB without any issue.

OP's issue isn't really the CPU spec related. You may call that config is not supported, but definitely can work on cMP.

Hmm interesting. Could it be there are different versions out there. I had the same with a MP4.1 and a W-Xeon. It only saw 24GB of Ram, after the upgrade to 5.1 and a X5680 it saw more.

Sometimes its strange with Intel CPU's in Apple hardware. i.e. I got an iMac 2008 with a Core2Duo 2.4 Ghz. I discovered the CPU is a Core2Duo Mobile E8135, according to Intel it should run at 2.66 Ghz. But Apple somehow ordered those CPU with a lower clock multiplier 9 insted of 10. They did the same with the E8335 in the 20" of 2008.