MP 1,1-5,1 Why is my 5.1 MP (flashed from 4.1 2009) halving my Ram?

[JRonk]

Hello,

First post here with a new old computer. I'm having an issue with my Mac Pro halving the amount of Ram. I assume it has to do with the kind of ram I'm using but could use some guidance. First of all, here's the specs

Originally a single Quad 2.93GHZ Nehalem. I flashed it to a 5.1 and installed a Xeon X5690 3.46GHz 6 core processor. All this went well, but as I understand, the MP (with the upgraded processor) should now be reading the memory as 1333MHz, rather than the 1066MHz. Also, each stick is 16 gigs. I have four of them for a total of 64 gigs. I tried it with only 3 16Gig sticks, and it still halved the ram. The ram I'm using I harvested from a computer of my dads. It is the following:

Vengeance® Low Profile — 16GB Dual Channel DDR3 Memory Kit

Vengeance Low Profile heat spreaders have a reduced height of 1.03 (26.25mm). They're designed for high-performance systems with extra-large CPU coolers, small form factor system builds, or any other space-constrained application where standard Vengeance memory might not fit.

www.corsair.com

I also tried a PRam reset (holding down command/option PR) but that neither changed the speed of the ram or the fact that each Ram stick is apparently halved in size.

Am I okay running this ram if I'm okay with 32Gigs and 1066MHz? (I'm using it for recording music. Probably won't peak out the ram anyway) But. . . .

I thought I'd try to utilize the full ram if possible. I don't know exactly which macs can and cant's use dual ram sticks like these or can't utilize the 1333mHz. ???

 

[HaypurTiryading]

Could you look at your dimms and tell us ranks? Are they 1R x 4 - 2R x + or 4R x 4?

Apple's Recommendation:

• PC3-10600E, 1333 MHz, DDR3 SDRAM UDIMMs
• Error-correcting code (ECC)
• 72-bit wide, 240-pin ECC modules
• 36 ICs maximum per ECC UDIMM

If I'm not wrong, 4 dimm installation slowing the speed and reducing the channel from 3 to 2. Also 3 dimm installed, 4R x 4 rank rams will not work at full speed. 2R x 4 or lower ranks required due to 36 ICs max requirement. Could you try one dimm installation?

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[MarkC426]

Post a couple of screenshots:
1. From the Apple/about this mac, select the memory tab.
2. System report/memory section.

 

[Macschrauber]

3 continuous nvRam Resets in a row will re read the spd data of the Ram sticks. Worth a try

 

[MIKX]

Like this . . . . ( read the small black print ! ) shut down before you do tHE "Three Consecutive Chimes NVRAM RESET".

 

[JRonk]

Okay, posted a couple screen shots. Thanks everybody for the info. I did the PRAM/NVRAM reset for 3 chimes and still have the issue. I have read through one of those long threads but didn't find what I was looking for. Maybe some one will see something in one of those screen shots that I'm overlooking.

 

[tsialex]

Okay, posted a couple screen shots. Thanks everybody for the info. I did the PRAM/NVRAM reset for 3 chimes and still have the issue. I have read through one of those long threads but didn't find what I was looking for. Maybe some one will see something in one of those screen shots that I'm overlooking.

Post a picture of the label of the DIMM, without it we can't know if your RAM is supported, if have compatible rank/density/etc.

 

[Analog Kid]

Okay, posted a couple screen shots. Thanks everybody for the info. I did the PRAM/NVRAM reset for 3 chimes and still have the issue. I have read through one of those long threads but didn't find what I was looking for. Maybe some one will see something in one of those screen shots that I'm overlooking.

I think everything is right as it should be. The Corsair 16GB kit is two 8GB sticks. So if you have two kits installed then you have 32GB of RAM installed as 4 x 8GB sticks.

Your screen shot says the Mac accepts 1066MHz modules, so that's probably where it will max out.
I apparently got this bit wrong, see below.

 

[JRonk]

Thanks very much for the info so far. It's easier for me to just write what the Corsair label says:

(long part number, like in link above)

16GB (2X8GB) 652174 131203014
1600MHz 10-10-10-27 1.5V ver 7.21

As I understand the Xeon X5690 processor should be able to use 1333MHz ram, so this 1600MHz ram should downclock to 1333MHz?

Also, I guess I just don't understand exactly what dual channel ram is? Is it designed for a dual processor perhaps? Or a motherboard especially to use dual channel ram?

 

[tsialex]

Thanks very much for the info so far. It's easier for me to just write what the Corsair label says:

(long part number, like in link above)

16GB (2X8GB) 652174 131203014
1600MHz 10-10-10-27 1.5V ver 7.21

As I understand the Xeon X5690 processor should be able to use 1333MHz ram, so this 1600MHz ram should downclock to 1333MHz?

Also, I guess I just don't understand exactly what dual channel ram is? Is it designed for a dual processor perhaps? Or a motherboard especially to use dual channel ram?

It's 8GB modules, 4 DIMMs = 32GB.

1600MHz works at 1333MHz with a X5690. If it's working below 1333MHz, the rank of the DIMM is not ideal and the memory controller downgrades the frequency.

MP5,1 is tri-channel, three DIMMs are accessed by the memory controller simultaneously. If you use 4 DIMMs, the rank and quantity of the DRAM chips on each DIMM will make a lot of difference and sometimes you downgrade the memory controller frequency and can even go back to dual-channel, having more performance penalties than expected.

Edit for clarification.

 

[flowrider]

^^^^Not sure that's true. Yes there is a pereformance penalty, but it is my understanding that when using four dimms, dimm #3 and #4 are shared in Channel three. Channels one and two remain unaffected.

Lou

 

[MacUser2525]

Hello,

First post here with a new old computer. I'm having an issue with my Mac Pro halving the amount of Ram. I assume it has to do with the kind of ram I'm using but could use some guidance. First of all, here's the specs

Originally a single Quad 2.93GHZ Nehalem. I flashed it to a 5.1 and installed a Xeon X5690 3.46GHz 6 core processor. All this went well, but as I understand, the MP (with the upgraded processor) should now be reading the memory as 1333MHz, rather than the 1066MHz. Also, each stick is 16 gigs. I have four of them for a total of 64 gigs. I tried it with only 3 16Gig sticks, and it still halved the ram. The ram I'm using I harvested from a computer of my dads. It is the following:

Vengeance® Low Profile — 16GB Dual Channel DDR3 Memory Kit

Vengeance Low Profile heat spreaders have a reduced height of 1.03 (26.25mm). They're designed for high-performance systems with extra-large CPU coolers, small form factor system builds, or any other space-constrained application where standard Vengeance memory might not fit.

www.corsair.com

I also tried a PRam reset (holding down command/option PR) but that neither changed the speed of the ram or the fact that each Ram stick is apparently halved in size.

Am I okay running this ram if I'm okay with 32Gigs and 1066MHz? (I'm using it for recording music. Probably won't peak out the ram anyway) But. . . .

I thought I'd try to utilize the full ram if possible. I don't know exactly which macs can and cant's use dual ram sticks like these or can't utilize the 1333mHz. ???

I do not think anyone has mentioned it but those sticks are not server ram with ECC either.

 

[tsialex]

^^^^Not sure that's true. Yes there is a pereformance penalty, but it is my understanding that when using four dimms, dimm #3 and #4 are shared in Channel three. Channels one and two remain unaffected.

Lou

For servers that have DPC>1, I agree with you, tri-channel still happens with 6 or 9 DIMMs, just with relaxed timings and slower memory controller access frequency.

The way Apple wired the 4th DIMM is not the same as usual Westmere servers that have DPC>1. Rank and quantity of DRAM chips are very important with MP4,1 or MP5,1, sometimes you almost have no penalty with the 4th slot sharing channel with the 3rd, while with slightly different DIMMs you have dual channel downgrade and slower frequency.

 

[Analog Kid]

I don't have much experience swapping processors and reflashing old Macs and may be misreading the report, but from the screenshot it looks like the Mac thinks it only accepts 1066MHz memory:

 

[tsialex]

I don't have much experience swapping processors and reflashing old Macs and may be misreading the report, but from the screenshot it looks like the Mac thinks it only accepts 1066MHz memory:

View attachment 919913

 

[Analog Kid]

View attachment 919914 View attachment 919915

That isn't what the screenshots posted above by @JRonk shows...

 

[tsialex]

That isn't what the screenshots posted above by @JRonk shows...

I explained why…

 

[Analog Kid]

I explained why…

So does that mean that what the Mac says it will accept changes depending on what memory is installed? I understood the "This Mac accepts" report to indicated what the hardware supports, and the detailed report to show what's recognized.

I'm clearly outside my experience here, though.

 

[tsialex]

So does that mean that what the Mac says it will accept changes depending on what memory is installed? I understood the "This Mac accepts" report to indicated what the hardware supports, and the detailed report to show what's recognized.

I'm clearly outside my experience here, though.

The first requirement is a Xeon processor that the memory controller supports 1333MHz, then the frequency/rank/density of the DIMM. 12-Core MP5,1 have the correct Xeons and memory from factory, btw, most if not all Apple original memory for MP5,1 is 1333MHz even if the Xeon only supports 1066MHz.

Westmere/Gulftown Xeons support 1333MHz to 800MHz DIMMs.

 

[MacUser2525]

So does that mean that what the Mac says it will accept changes depending on what memory is installed? I understood the "This Mac accepts" report to indicated what the hardware supports, and the detailed report to show what's recognized.

I'm clearly outside my experience here, though.

It depends on the processor installed too, it needs to have the support for faster ram enabled in the chip. Then you need to do the PRAM reset once the processor supporting it is installed and you will get the 1333 speed with ram rated for that, but never the 1600 them chips do not support it.

Edit: Alex beats me to it.

 

[Analog Kid]

The first requirement is a Xeon processor that the memory controller supports 1333MHz, then the frequency/rank/density of the DIMM. 12-Core MP5,1 have the correct Xeons and memory from factory, btw, most if not all Apple original memory for MP5,1 is 1333MHz even if the Xeon only supports 1066MHz.

Westmere/Gulftown Xeons support 1333MHz to 800MHz DIMMs.

It depends on the processor installed too, it needs to have the support for faster ram enabled in the chip. Then you need to do the PRAM reset once the processor supporting it is installed and you will get the 1333 speed with ram rated for that, but never the 1600 them chips do not support it.

Edit: Alex beats me to it.

Thanks. I edited my post above to avoid confusion...

 

[JRonk]

Okay, so I don't have the best ram. Thanks for all the info. So there are different versions of the X5690 processor, some of which have this faster ram allowance enabled and I happened to buy one that doesn't? Oh well. I'm not taking it out, because there's no problems and it seems to haul ass and run pretty cool.

 

[tsialex]

So there are different versions of the X5690 processor, some of which have this faster ram allowance enabled and I happened to buy one that doesn't?

No, just one, SLBVX.

 

[MacUser2525]

Okay, so I don't have the best ram. Thanks for all the info. So there are different versions of the X5690 processor, some of which have this faster ram allowance enabled and I happened to buy one that doesn't? Oh well. I'm not taking it out, because there's no problems and it seems to haul ass and run pretty cool.

No all of them are limited to 1333 in your machine, the only thing you lose is the ECC by using consumer instead of server ram.

 

[JRonk]

No all of them are limited to 1333 in your machine, the only thing you lose is the ECC by using consumer instead of server ram.

I didn't mean "limited" to 1333. I meant limited to 1066. I know the processor can't achieve the 1600MHz of the ram that I have. I just want it to be able to downclock to 1333MHz, which it should . . . (?)

I made sure to buy an X5690 processor with the "SLBVX" designation.

So, anyway, if I were intent on utilizing more ram in this machine, I'd have to find some more appropriate server ram . . okay. That's fine. I was just hoping to use what I already had first.

But I still don't understand why my computer says the max ram speed is 1066, when I have a processor installed that should be able to do more. So, can someone confirm that it should theoretically show 1333MHz in the "about this mac" settings only when I have the appropriate ram installed?

Alex says the first thing is having a processor where the memory controller is "enabled" for 1333MHz. If this is the issue, is there a way to remotely enable this, or do I have to take the processor out and use one of my trained rodents to flip a nearly invisible micro switch?