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w8ing4intelmacs

macrumors 6502a
Original poster
Feb 22, 2006
559
4
East Coast, US
I have a Mac Pro 5,1 2.8 single with 16GB (4x4GB).

I got a great price on a 16GB stick but it wasn't playing nice with the other memory. After doing research, I guess I got a 16GB RDIMM and my other memory are UDIMMs. So much for my cheap way of upgrading to 28GB.

So, do I keep the one stick of 16GB and sell the 4x4GB? There's the part of me that's afraid that RDIMMs are harder to come by and that even if I do buy more RDIMMs, they still won't play nice together.

Also, how can you tell if it's an RDIMM or UDIMM if it has a heatspreader covering it?
 

DeltaMac

macrumors G5
Jul 30, 2003
13,757
4,583
Delaware
All 16 GB sticks will be RDIMMs - don't think you will find UDIMM 16GB
You can't mix UDIMM and RDIMM
Some other info here, mostly about some other choices.
 

js2704

macrumors member
May 20, 2015
39
11
I have a Mac Pro 5,1 2.8 single with 16GB (4x4GB).

I got a great price on a 16GB stick but it wasn't playing nice with the other memory. After doing research, I guess I got a 16GB RDIMM and my other memory are UDIMMs. So much for my cheap way of upgrading to 28GB.

So, do I keep the one stick of 16GB and sell the 4x4GB? There's the part of me that's afraid that RDIMMs are harder to come by and that even if I do buy more RDIMMs, they still won't play nice together.

Also, how can you tell if it's an RDIMM or UDIMM if it has a heatspreader covering it?

If you got a good deal on the 16GB I'd sell it and pick up ex-server RAM on eBay - 8GB sticks are pretty reasonable and would play fine with the stock 4GBs so you could go from 12-24-32 incrementally
 

iBuildMacs

macrumors member
Dec 29, 2014
32
4
Original Apple RAM is ECC. It usually ends in E. UDIMM ends in U.

U - unregistered or unbuffered
E - ECC (error correcting code)
R - registered

There is ECC and non-ECC registered RAM. The same with unregistered; some are ECC, some not.

I recommend getting E or R. I have worked on thousands of Macs. Apple never ships with UDIMM. They always ship with ECC on the Mac Pros... or R in the case of 16GB modules.
 
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stjames70

macrumors regular
Jul 5, 2009
108
8
The official RAM for the 5,1 is Unregistered ECC RAM.

It is costlier and harder to find than Registered ECC RAM.

Buy all your RAM from one manufacturer and one source if you can help it -- it avoids compatibility problems.

My 5,1 runs 64GB of Registered Hynix DDR3 ECC 1333 MHz RAM. Do a search for it. Prices are reasonable.
 

h9826790

macrumors P6
Apr 3, 2014
16,656
8,587
Hong Kong
Apple never ships with UDIMM. They always ship with ECC on the Mac Pros... or R in the case of 16GB modules.

Please check the manual before you "assume" the answer is right. The following is copied from the 4,1 Apple tech guide. AFAIK, the 5,1 still use the same type of RAM, just a bit faster.

Mac Pro (Early 2009) comes with a minimum of 3 GB of memory, installed as three 1 GB unbuffered dual inline memory modules (UDIMMs).

DIMMs must fit these specifications:

  • PC3-8500,1066 MHz, DDR3 SDRAM UDIMMs

  • 72-bit wide, 240-pin modules

  • 18 memory ICs maximum per UDIMM

  • Error-correcting code (ECC)


Anyway, I think only the new Mac Pro may come with the RDIMM (4x16G), and all old Mac Pro comes with UDIMM (stock max 8x8G, all UDIMM) .
 
Last edited:

666sheep

macrumors 68040
Dec 7, 2009
3,686
292
Poland
Original Apple RAM is ECC. It usually ends in E. UDIMM ends in U.

U - unregistered or unbuffered
E - ECC (error correcting code)
R - registered

There is ECC and non-ECC registered RAM. The same with unregistered; some are ECC, some not.

I recommend getting E or R. I have worked on thousands of Macs. Apple never ships with UDIMM. They always ship with ECC on the Mac Pros... or R in the case of 16GB modules.


Haha, "E" e.g. in "PC3-10600E" stands for ECC UDIMM.
 

lowendlinux

macrumors 603
Sep 24, 2014
5,460
6,788
Germany
Please check the manual before you "assume" the answer is right. The following is copied from the 4,1 Apple tech guide. AFAIK, the 5,1 still use the same type of RAM, just a bit faster.

Mac Pro (Early 2009) comes with a minimum of 3 GB of memory, installed as three 1 GB unbuffered dual inline memory modules (UDIMMs).

DIMMs must fit these specifications:

  • PC3-8500,1066 MHz, DDR3 SDRAM UDIMMs

  • 72-bit wide, 240-pin modules

  • 18 memory ICs maximum per UDIMM

  • Error-correcting code (ECC)


Anyway, I think only the new Mac Pro may come with the RDIMM (4x16G), and all old Mac Pro comes with UDIMM (stock max 8x8G, all UDIMM) .

He builds Mac's ;)
 

lie2me

macrumors member
Apr 23, 2010
97
40
Somewhere
I think the stock hardware for the 2009 Mac Pro cheese grader (4.1) is slightly different than the 2010 and 2012 (5.1) models, particularly the CPU hardware trays. The sequence of comments in this forum can be confusing. According to Apple, the 2009 Mac Pro does not support registered DIMMs. It may be the memory controller on the stock 2009 CPU boards cannot adapt to the timing of registered memory. It is not clear to me that a firmware update of a 2009 Mac Pro will change that either. Accordingly, with a 2009 Mac Pro, it is better to stick with unbuffered DIMMs or unregistered DIMMs. The 2010 and 2012 Mac Pros seem to accommodate one or the other but not both registered and unregistered DIMMs at the same time. Any DIMM used in a MAC pro should have ECC capability, whether it is registered or not. Not sure a non-ECC memory DIMM can be used properly in a Mac Pro.
 

tsialex

Contributor
Jun 13, 2016
13,455
13,601
I think the stock hardware for the 2009 Mac Pro cheese grader (4.1) is slightly different than the 2010 and 2012 (5.1) models, particularly the CPU hardware trays. The sequence of comments in this forum can be confusing. According to Apple, the 2009 Mac Pro does not support registered DIMMs. It may be the memory controller on the stock 2009 CPU boards cannot adapt to the timing of registered memory.

It's supported, just not a config from Apple.

early-2009 and mid-2010/mid-2012 have the exact same chipsets. Single CPU and dual CPU trays have different northbridges and dual CPU trays support more memory, but same types of DIMM.

It is not clear to me that a firmware update of a 2009 Mac Pro will change that either. Accordingly, with a 2009 Mac Pro, it is better to stick with unbuffered DIMMs or unregistered DIMMs.

Memory support is the same for early-2009, mid-2010, mid-2012 with same firmware and same processors.

The 2010 and 2012 Mac Pros seem to accommodate one or the other but not both registered and unregistered DIMMs at the same time. Any DIMM used in a MAC pro should have ECC capability, whether it is registered or not. Not sure a non-ECC memory DIMM can be used properly in a Mac Pro.

Yes, you can use non-ECC memory. Just don't mix memory types, always use the same type and pay attention to rank

Edit:

While you can use non-ECC memory, you shouldn't. Don't install NON-ECC DIMMs to a Mac Pro, doing so eliminates most of the reliability of the memory and consequently of your Mac Pro.

Buy 1333MHz ECC 2Rx4 RDIMMs for your Mac Pro, forget anything else.
 
Last edited:

guys5.1ram

macrumors newbie
Aug 2, 2022
3
0
It's supported, just not a config from Apple.

early-2009 and mid-2010/mid-2012 have the exact same chipsets. Single CPU and dual CPU trays have different northbridges and dual CPU trays support more memory, but same types of DIMM.



Memory support is the same for early-2009, mid-2010, mid-2012 with same firmware and same processors.



Yes, you can use non-ECC memory. Just don't mix memory types, always use the same type and pay attention to rank.
Hey. I read your entry here saying it's ok to use non-ECC memory in a (2012) 5.1 mac pro. I just put in 64 gigs all by the same company. My question is would there be any benefit to using ECC / Registered memory in my 2012 that's really running nothing but Logic Pro X? Thank you. Preciate your time.
 

theMarble

macrumors 65816
Sep 27, 2020
1,023
1,509
Earth, Sol System, Alpha Quadrant
Hey. I read your entry here saying it's ok to use non-ECC memory in a (2012) 5.1 mac pro. I just put in 64 gigs all by the same company. My question is would there be any benefit to using ECC / Registered memory in my 2012 that's really running nothing but Logic Pro X? Thank you. Preciate your time.
ECC means Error Checking and Correction. This means that it's far less likely for memory errors and crashes to happen. Not necessary in a computer, but is critical on servers that run 24/7 and any mission-critical work (where even a few minutes of downtime could cost thousands of dollars.). Lots of workstations run ECC as they (overall) tend to be more reliable day-to-day than regular DIMM's. The reason Gaming/Home PC's don't utilise ECC is that memory speed is worse than normal DIMMs, however on a MP that only uses DDR3 1333, that doesn't matter as much.
 

tsialex

Contributor
Jun 13, 2016
13,455
13,601
Hey. I read your entry here saying it's ok to use non-ECC memory in a (2012) 5.1 mac pro. I just put in 64 gigs all by the same company. My question is would there be any benefit to using ECC / Registered memory in my 2012 that's really running nothing but Logic Pro X? Thank you. Preciate your time.
One of the things that make a Mac Pro extremely reliable are the ECC UDIMMs (or ECC RDIMMs), since the ECC detects most, if not almost all, common memory problems. Bit flips that you can only know that are happening when and if your computer crashes, are easily identified by the ECC circuit. ECC is practically a basic requirement for a workstation.

It's a dual or single CPU? I don't think that you can find 16GB UDIMMs NON-ECC PC10600 for a single, 4x16GB, but it's possible to find for a dual, 8x8GB UDIMMs NON-ECC PC10600.

I wouldn't install NON-ECC memory with any of my Mac Pros. Buy 1333MHz ECC 2Rx4 RDIMMs for your Mac Pro, forget anything else.
 

guys5.1ram

macrumors newbie
Aug 2, 2022
3
0
One of the things that make a Mac Pro extremely reliable are the ECC UDIMMs (or ECC RDIMMs), since the ECC detects most, if not almost all, common memory problems. Bit flips that you can only know that are happening when and if your computer crashes, are easily identified by the ECC circuit. ECC is practically a basic requirement for a workstation.

It's a dual or single CPU? I don't think that you can find 16GB UDIMMs NON-ECC PC10600 for a single, 4x16GB, but it's possible to find for a dual, 8x8GB UDIMMs NON-ECC PC10600.

I wouldn't install NON-ECC memory with any of my Mac Pros. Buy 1333MHz ECC 2Rx4 RDIMMs for your Mac Pro, forget anything else.
Hey. Preciate your response. What you just said is exactly what I found after leaving you the question yesterday. I went back in the studio and the mac pro wouldn't start up. Returning the non-ECC ram today.
I put the ram I had in and all were ECC and everything worked fine again. All the ram I was using was ECC because ECC was enabled again.
I'm buying DMS ram which I had some of it in the computer already. ECC and guaranteed to work on my 5.1 Mac Pro.
Once again thanks for the response and advice that somehow was sent from you over the universe because I took your advise without hearing your advise. Preciate.
 

guys5.1ram

macrumors newbie
Aug 2, 2022
3
0
Hey. Preciate your response. What you just said is exactly what I found after leaving you the question yesterday. I went back in the studio and the mac pro wouldn't start up. Returning the non-ECC ram today.
I put the ram I had in and all were ECC and everything worked fine again. All the ram I was using was ECC because ECC was enabled again.
I'm buying DMS ram which I had some of it in the computer already. ECC and guaranteed to work on my 5.1 Mac Pro.
Once again thanks for the response and advice that somehow was sent from you over the universe because I took your advise without hearing your advise. Preciate.
Oh yeah forgot about the CPU question. I'm running Dual CPU's / 12 core.
 
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