RAM-mixing issues

[talino]

Hello,

I have a quad-core 2.66 Mac Pro 2009 Nehalem running Lion. For over a year it has been running with 24gb with no issues:

2 x 4gb Crucial
2 x 8gb OWC

After a while I started to get startup issues and other weird behaviors, and after several switching and reseating it turned out one of the OWC modules was causing the error.

The Mac kept running fine with 16gb (2x4 + 8) while I ordered two new 8gb modules. I was hoping to use a 3x8gb config, and maybe add one of the 4gb modules in the last slot for the unusual total of 28gb.

However, the Mac refuses to boot (flashing light) when I mix the new modules (Samsung) with the OWC module. So, with the Crucial modules out of the equation:

1 x 8gb OWC -> Startup OK
2 x 8gb Samsung -> Startup OK
3 x 8gb (all of the above together) -> Flashing light

I've tried many different combinations, module order etc, and even tried to mix the Samsungs with the Crucials, nothing helped.

I've also tried the system reset procedure recommended by Apple (keeping the power cord disconnected for 15 seconds etc).

Any ideas what I could do next? I've just invested in two 8gb modules only to find myself at the exact same RAM installed as I had in the first place...

Thanks.

 

[RCZ]

you need to check if the speed of the modules is equal.. and if the modules are all ECC (Registered) or not..

 

[Marty62]

The MP's get et a bit "fussy" about mixing brands of ram, been there !

I just added and 8Gb "Hynix" stick to my MP after searching for the exact
same brand / spec.
There is one "digit" different between them, new one has an "L" in it's
long part number, BUT it works and was close enough

M.

 

[xcodeSyn]

Any ideas what I could do next? I've just invested in two 8gb modules only to find myself at the exact same RAM installed as I had in the first place...

Do any of your 8GB modules look like this:

The above image is RDIMM and not compatible with UDIMM that looks like:

BTW most memeory modules have lifetime warranty, and you should contact OWC for replacement of the defective memory.

 

[talino]

All modules are 1066 ECC specifically ordered for my Mac Pro Nehalem, so I don't think that's the issue.

The new modules (from Samsung) are reported like this by System Info, just like the OWC one (except for the manufacturer, of course):

Size: 8 GB
Type: DDR3 ECC
Speed: 1066 MHz
Status: OK
Manufacturer: 0x80CE

I live in France and shuffling modules between here and Illinois, and dealing with custom forms and such, is such a major headache here that I prefer just buying new RAM. I already paid double customs once for my SSD from OWC...

Any other ideas, maybe?

 

[xcodeSyn]

All modules are 1066 ECC specifically ordered for my Mac Pro Nehalem, so I don't think that's the issue.

The new modules (from Samsung) are reported like this by System Info, just like the OWC one (except for the manufacturer, of course)

You did not really answer the question because the System Report from Mac Pro can not tell whether the memory modules are RDIMMs or UDIMMs. I know this because I have used both types in my machine before. I could be wrong of course, but I still think mixing different types of DIMM is the more likely explanation. At least find the product number on the memory module and find out its DIMM type online. People in the past have reported no problem when mixing different memory speeds or even ECC and non-ECC (although not recommended) memory modules as long as they are UDIMMs.

 

[talino]

I didn't answer the question because I couldn't see enough similarities between the photos you included and what I have here. I've taken pics of the two module types I have, in the hope you could identify them as either RDIMM or UDIMM, as I haven't a clue.

 

[xcodeSyn]

I didn't answer the question because I couldn't see enough similarities between the photos you included and what I have here. I've taken pics of the two module types I have, in the hope you could identify them as either RDIMM or UDIMM, as I haven't a clue.

Just as I suspected, the bottom two modules are RDIMMs, as it clearly showed ECC REG as registered module on the heat spreader. So you don't even need to remove the heat spreader to confirm them as RDIMMs. You need to return these two for UDIMMs as unbuffered memoery modules.

 

[talino]

I've just look at the specs and realized I made a mistake in what I ordered. I asked for "8.0GB PC8500 DDR3 ECC 1066MHz 240 Pin" while my current OWC module is a "8.0GB PC10600 DDR3 ECC 1333MHz 240 Pin". Isn't that the issue? I'm not sure I understand the UDIMM/RDIMM difference. Isn't ECC what it's supposed to say on the module?

 

[Marty62]

PC10600 DDR3 ECC 1333MHz 240 Pin

Is what you need for sure !

That's exactly what I have but "Hynix" brand to match the others.

( mine look very much like the Samsung, with the heat sink metal covers )

Sorry for your mistake, easily done and hope you can exchange them.

M.

 

[xcodeSyn]

Isn't that the issue? I'm not sure I understand the UDIMM/RDIMM difference. Isn't ECC what it's supposed to say on the module?

Mixing 1066 and 1333MHz memory is not a big deal because they'll just fall to the lower speed 1066Mhz which is also the max speed your current CPU can handle. If there is no price difference, then for sure order the higher memory speed modules for possible future CPU upgrade.

UDIMM means unbuffered memory module while RDIMM means registered module. If you remove the heat spreader of the Samsung module, you'll see the major difference as illustrated in my previous image links. Generally speaking, registered memory is always ECC, but not for UDIMMs. Most consumer PCs use non-ECC UDIMMs while 2009 and later MPs use ECC UDIMMs as standard memory. That's why you have to order modules with 9 memory chips as they are ECC UDIMMs, non-ECC UDIMMs generally have only 8 memory chips without the ECC chip.

 

[xcodeSyn]

I just found the product link for your Samsung memory modules, and the seller even use the wrong picture of a non-ECC module for the product and no mentioning of registered module at all. Here is an example of a compatible 8GB ECC UDIMM made by Kingston, at least the seller tells us it's unbuffered and the picture is correct with 9 chips.

 

[talino]

OK, the person who sold me the new (Samsung) modules just wrote back, seeminlgy confirming what you've written. He says that my older modules (OWC) are "not validated by Apple because they are non REG", and that REG and non-REG can't be mixed (I'm translating from French here...)

He says his supplier can't exchange the Samsung modules for non-REG types because he only deals with Apple-certified RAM.

Three questions arise:

1. Does this make sense?
2. How come both OWC and Crucial (which worked together fine on my machine) sell non-Apple-certified modules?
3. If I order two more identical Samsung REG modules to go with my new modules, ditching the OWC modules altogether, will there be a noticeable change in performance (adopting 1066 instead of 1333 Mhz speed)?

Thanks again.

 

[xcodeSyn]

Three questions arise:

1. Does this make sense?
2. How come both OWC and Crucial (which worked together fine on my machine) sell non-Apple-certified modules?
3. If I order two more identical Samsung REG modules to go with my new modules, ditching the OWC modules altogether, will there be a noticeable change in performance (adopting 1066 instead of 1333 Mhz speed)?

1. No, it doesn't because it is he that sells non-Apple certified registered memory modules. You should forward this guy's email to Apple and see how Apple responds.
2. OWC always charges higher prices for their products simply because compared to Apple's outrageous prices, theirs are not so bad and always compatible with Mac models because they actually do the testing on the products they sell. I'm always amazed that people from other continents would buy from OWC even when there may be better choices locally, but at least that speaks something about the reputation of OWC. This guy apparently picked the wrong vendor to spread his nonsense.
3. If you could get your refund, that would be the best choice since I'd never deal with a dishonest vendor like this again. There won't be any difference in performance in terms of memory speed since your CPU can only handle 1066 MHz. If you are certain that you'll never upgrade the CPU and/or memory again, then get another two sticks and make this guy happy.

 

[talino]

Maybe it's a model-specific issue here? This post in the Apple Support Forums says:

Apple indicates that registered DIMMs are supported by Mac Pro version 5.1 - 2010 models. They have not provided the same indication for Mac Pro version 4.1 - 2009 models. WIth that said, firmware on version 4.1 macs may be able to be upgraded to support RDIMMs.

Maybe the confusion comes from my model (which is 4,1)? I have two opposing point-of-views which are defended just as vigorously, and I'm in no position to make an informed decision. And I don't have the luxury of spending another €200 just to let it lie

 

[Marty62]

Maybe it's a model-specific issue here? This post in the Apple Support Forums says:



Maybe the confusion comes from my model (which is 4,1)? I have two opposing point-of-views which are defended just as vigorously, and I'm in no position to make an informed decision. And I don't have the luxury of spending another €200 just to let it lie

Hi Talino,

You said that you checked your order and that YOU got it wrong ??

Do I have that correct?

So, other people "calling out" the seller makes absolutely NO sense whatsoever, does it ?

If you indeed ordered the "wrong type" - and sorry if I didn't follow correctly - then it's
up to him if he tries to help with an exchange or not.

2009 MP Ram IS different, you seem to have received Ram for 2010-12 MP's, which is why the
Ram looks exactly like mine, heat sinks and all.

Why not "Flash" the MP to 5,1 and take advantage of the little speed bump up to 1,333 ??

I understand that you're out of pocket and that's NOT cool, was not the fault of the seller though ??

Perhaps a VERY apologetic email would get you out of the sh** with him ?

It's worked before for me.

Or get two more 1,333's from him and move on the OWC sticks ?

That's my 2 C's

M.

 

[talino]

I was wrong in ordering the 1066 Mhz module instead of the 1333 Mhz one, but everyone seems to agree that mixing them isn't the source of problem. It's the fact that one set is RDIMM and another UDIMM, a subtlety I wasn't remotely aware of. I'm not looking for someone to blame. I'm trying to understand a very technical issue so that I could ask the right person for an exchange, that's all.

 

[Marty62]

I was wrong in ordering the 1066 Mhz module instead of the 1333 Mhz one, but everyone seems to agree that mixing them isn't the source of problem. It's the fact that one set is RDIMM and another UDIMM, a subtlety I wasn't remotely aware of. I'm not looking for someone to blame. I'm trying to understand a very technical issue so that I could ask the right person for an exchange, that's all.

Fair enough

I didn't follow the R or U Dimm info OR how it can mix or not.

I am no RAM guru, I just order "exactly" the same as is in my machine but
NOT from Apple !

My last MP uses DDR 800 FB Dimm's and they are SO specific you just
cannot get that wrong !
M.

 

[talino]

Just for the record, after two weeks of waiting, the vendor agreed to take back the modules and send me a couple of 8gb Kingston modules, for a little extra cost. These are working just fine alongside the OWC module (shown above) and even together with my 4GB Crucial 2RX8 PC3-8500E module, for a funny total of 28gb of RAM.

Thanks to everyone for their help.