MP 1,1-5,1 5,1 Mac Pro won’t address 1333MHz RAM

[Dwight__SCHRUTE]

Hello all! First time poster here.

I have a 2009 4,1 Mac Pro that I’ve flashed to 5,1. It has dual 2.66 X5550 quad core Xeon processors. I’ve installed 8x 4GB 1333MHz PC3 - 10600R DIMMs in it. The computer lists RAM speed as 1066MHz (and only lists 24GB).

According to Wikipedia, the X5550 does support 1333MHz sticks. I’ve reset PRAM and it didn’t do anything. Any ideas on how I can get the MP to address the faster RAM?

thank you

 

[h9826790]

Sounds like your DIMM are 4Rx4, but not 2Rx4.

 

[solaris8x86]

I had that 2.66 model. The RAM speed is not 1333 I think is normal.

 

[Dwight__SCHRUTE]

Sounds like your DIMM are 4Rx4, but not 2Rx4.

Could you expand on this?

 

[bsbeamer]

Read this:

cMP & nMP {MacPro 4,1 & 5,1} Memory Upgrade Compatibility and FAQ

Here is the start to a mega thread of memory upgrades and FAQ Please feel free to post your working configurations along with your brand and model numbers. A single W36xx CPU can support up to 56GB memory (3x16 + 8) A single X56xx CPU can support up to 64GB memory (4x16) A dual X56xx CPU can...

forums.macrumors.com

 

[JedNZ]

I just replaced the 1066MHz ram in two spare cMP 4,1>5,1 cMPs with 1333MHz DIMMs and typically on first boot up the new ram shows as 1066MHz. After doing an NVRAM reset (hold down Cmd+Opt+P+R continuously for three full restarts) and they’re now registering at 1333MHz. Have you tried resetting NVRAM?

 

[h9826790]

I had that 2.66 model. The RAM speed is not 1333 I think is normal.

Intel says it support 1333MHz DIMM

Intel® Core™ Processors, FPGAs, GPUs, Networking, Software

Browse Intel product information for Intel® Core™ processors, Intel® Xeon® processors, Intel® Arc™ graphics and more.

ark.intel.com

Have you tried resetting NVRAM?

OP said he did that in post #1

Could you expand on this?

Check the sticker on the DIMM

 

[Monotremata]

Theres a little more to the weird memory bus architecture of the Nehalem CPU than just popping in memory and having it take off at full speed apparently.. It might even be because youre using all 8 instead of two banks of 3.
https://media.kingston.com/images/branded/MKF_102_Nahalem_Ref.pdf

 

[atonaldenim]

Could you expand on this?

Always use dual rank (2Rx4) RAM in the Mac Pro, not quad rank (4Rx4).

I don't know what that means exactly, but I've had problems with 4Rx4 RAM showing up at a slower speed in Mac Pro 5,1. When I exchanged it for 2Rx4 RAM, that worked perfectly.

 

[jscipione]

Take out DIMMs 4 and 8 (closest to CPUs) and see if the memory is listed as 1333mhz. If so, then you know that you have got quad rank memory.

 

[Monkeynuts*]

Hello everyone,
Seems I'm another 5 years and change late to the show, but hey-ho. I bought 6x Samsung 16Gb 2Rx4 PC3L 16000R 1333Mhz RAM for my 2009 Mac Pro, and it's showing the speed as 1066Mhz. Any clue why? It's a flashed 4,1 -> 5,1 with 2x 2.93 Xeons.

Any help would be greatly appreciated,

Thanks.

 

[JedNZ]

What’s your native firmware? Only
MP51.0089.B0 and later support the faster 1333MHz ram. And only Westmere Xeon CPUs (X56xx series, e.g., X5670, X5680, X5690) support 1333MHz RAM.
If you meet that criteria then resetting the NVRAM and SMC might be the solution.

 

[tsialex]

Any clue why? It's a flashed 4,1 -> 5,1 with 2x 2.93 Xeons.

You need to check is the Xeon model you have even supports 1333 MHz DIMMs. You can open Terminal and run sysctl -n machdep.cpu.brand_string to know the model installed.

Most 2.93 MHz Quad-core Xeons only work up to 1066 MHz, even the Westmere ones:

https://forums.macrumors.com/thread...ity-list.1954766/?post=22540971#:~:text=X5647

Since all rules have an exception, the X5570 is a 2.93 MHz Xeon that supports 1333 MHz:

https://forums.macrumors.com/thread...ity-list.1954766/?post=22540971#:~:text=X5570

So, check if you have to upgrade your Xeons too to a model that supports 1333 MHz DIMMs. If you already have a Xeon that supports 1333 MHz DIMMs, do a deep NVRAM reset (reset the NVRAM continously until you hear the 5th chime) to enable the faster bus speed.

What’s your native firmware? Only
MP51.0089.B0 and later support the faster 1333MHz ram.

This is incorrect, all MacPro5,1 BootROM releases support 2Rx4 1333 MHz DIMMs when a Xeon that supports 6.4 GT/s bus speed is installed.

And only Westmere Xeon CPUs (X56xx series, e.g., X5670, X5680, X5690) support 1333MHz RAM.

Incorrect too, there are several models of Nehalem Xeons with 6.4 GT/s QPI links, these support 1333 MHz DIMMs and will work at 1333 MHz with any MacPro5,1 BootROM release:

https://forums.macrumors.com/threads/mac-pro-cpu-compatibility-list.1954766/?post=22540971#:~:text=W5590

Btw, there are also Westmere Xeons that only work up to 1066 MHz DIMMs.

 

[Monkeynuts*]

You need to check is the Xeon model you have even supports 1333 MHz DIMMs. You can open Terminal and run sysctl -n machdep.cpu.brand_string to know the model installed.

Most 2.93 MHz Quad-core Xeons only work up to 1066 MHz, even the Westmere ones:

https://forums.macrumors.com/thread...ity-list.1954766/?post=22540971#:~:text=X5647

Since all rules have an exception, the X5570 is a 2.93 MHz Xeon that supports 1333 MHz:

https://forums.macrumors.com/thread...ity-list.1954766/?post=22540971#:~:text=X5570

So, check if you have to upgrade your Xeons too to a model that supports 1333 MHz DIMMs. If you already have a Xeon that supports 1333 MHz DIMMs, do a deep NVRAM reset (reset the NVRAM continously until you hear the 5th chime) to enable the faster bus speed.



This is incorrect, all MacPro5,1 BootROM releases support 2Rx4 1333 MHz DIMMs when a Xeon that supports 6.4 GT/s bus speed is installed.



Incorrect too, there are several models of Nehalem Xeons with 6.4 GT/s QPI links, these support 1333 MHz DIMMs and will work at 1333 MHz with any MacPro5,1 BootROM release:

https://forums.macrumors.com/threads/mac-pro-cpu-compatibility-list.1954766/?post=22540971#:~:text=W5590

Btw, there are also Westmere Xeons that only work up to 1066 MHz DIMMs.

I have those Xeons, the X5570s and did the hard reset as suggested. Still showing 1066MHz.. =/

Thanks for the advice.

*Checked the link and that would make them Nehalem Xeons, correct?

 

[tsialex]

I have those Xeons, the X5570s and did the hard reset as suggested. Still showing 1066MHz.. =/

Thanks for the advice.

Test with just one DIMM installed, do the NVRAM deep reset again.

Inspect each one to see if all are 2Rx4, if you have one 4Rx4, the memory controller will downgrade to 1066 MHz.

 

[Monkeynuts*]

Test with just one DIMM installed, do the NVRAM deep reset again.

Inspect each one to see if all are 2Rx4, if you have one 4Rx4, the memory controller will downgrade to 1066 MHz.

Hum... I checked all the RAM modules when I got them to make sure that they were 2Rx4, and not 4Rx4. I even verified this with the seller. I'll check again though that is now a bit of a pain in the butt as I've just added heatsinks...

I'll try with one stick tomorrow and report back. Late here now...

Thanks as ever for your continual online support, feedback and advice, tsialex.

Much appreciated,

Regards

 

[Monkeynuts*]

Test with just one DIMM installed, do the NVRAM deep reset again.

Inspect each one to see if all are 2Rx4, if you have one 4Rx4, the memory controller will downgrade to 1066 MHz.

Checked. All are 2Rx4. Tried resetting NVRAM with just one stick. Still showing 1066MHz.

I'm stumped.

 

[tsialex]

Checked. All are 2Rx4. Tried resetting NVRAM with just one stick. Still showing 1066MHz.

I'm stumped.

Do you have a different model of 1333 MHz DIMM to test? Check the original DIMMs, Apple installed 1333 MHz DIMMs to a lot of mid-2010/mid-2012 Mac Pros.