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Samsung 16G DDR3 1333 ECC REG 2RX4 PC3L-10600R
Just wanted to confirm that it's working on a 4,1 perfectly. I'll get back after flashing to 5,1 with speeds etc.
 
Sharing some interesting results from the single cpu test bench...

x5677 Geekbench 4 64-bit single core - 2009 - x58 chipset
16x16x16 - 8.82 GB/s memory copy 13.7 GB/sec bandwidth
16x16x16x16 7.2 GB/sec memory copy 12.2 GB/sec bandwidth
16x16x16x8 5.67 GB/sec memory copy 8.0 GB/Sec bandwidth

990x Geekbench 4 64-bit single core - 2009 - x58 chipset
16x16x16 - 8.0 GB/sec memory copy 13.3 GB/sec bandwidth
16x16x16x8 7.97 GB/sec memory copy 13.2GB/sec bandwidth
16x16x16x16 - n/a

Curious if you can re-run these tests using Disk Speed Test or AJA System Test after making a RAM Disk?! Or just a quick general one with you current settings?
I'm getting totally different #'s than you are.
I think your #'s show CPU -> RAM where i'd like to see RAM -> RAM DISK
 
OK, ALL IS WELL.
But I thought I might leave this post up as it was a curious issue.

I ended up with the 16GB RAM in slots #1 and #3. They both worked just fine.
A few hours later I thought, what if I put the 16GB back into #2 and add an original 8GB to #3??
First i relocated the 16GB to #2 and tried re-booting.
IT WORKED! No idea what happened over the 2-3 hours while one 16GB was in slot#3. We'll see if it works tomorrow from a cold startup.
FYI-Don't try mixing 16's with 8's. As has been mentioned here, Mac Pro no like!


***Original post***

I seem to be having trouble with my new RAM.

I recently purchased x2 16GB 1333MHz DDR3 PC3-10600 ECC from OWC for my MacPro5,1.

My previous RAM consisted of 3x 8GB 1333MHz DDR3 PC3-10600 ECC also from OWC.
I had the RAM installed in the first three slots from front to back. Never any issues with the 3x 8GB.

I installed the two 16GB sticks into slots #1 and #2 and only the 16GB in slot #1 showed up on About This Mac. There is also a bright LED lit up next to the RAM in slot #2.

To check if one of the sticks was bad, I installed each one separately into slot #1 and rebooted. Both 16GB sticks worked just fine in slot #1.
I then tried installing the RAM in slots #1 and #3 and finally both showed up.

I ran Geekbench 4 64-bit and the multicore scores were:
x3 8GB = 24GB RAM (slots #1, #2, and #3)....15195 (original set up)
x1 16GB RAM (slot #1)......112195
x2 16GB (slots #1 and #2)-only 16GB RAM working in #1.....112000
x2 16GB = 32GB RAM (slots #1 and #3)….141000

What is going on? I have read that MacPro5,1 RAM should be installed from the front #1, to the back #4, with best results using matching RAM and only in the first three slots.
Why is the 16GB RAM in slot #2 not being recognized and has the LED lit up?

I have a W3690 6-core 3.46ghz CPU. No problems with x3 8GBs.
 
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We should be testing out the larger Samsung M386B8G70DE0-YH9
64GB DDR3-1333 LRDIMM PC3L-10600L Octa Rank x4 Module
Samsung_M386B8G70DE0-YH93_64Gb_Memory_unit_WisetekMarket_1024x1024.jpg
 
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cMP (Early 2009) 5,1 Xeon X5675 3.06GHz (macOS 10.12.6) 32GB
Confirming these work w/o issue:
Using 4X 8GB 1333 DDR3 PC3-10600 RDIMM HP Server "pulls" ($58 on ebay)
HP part# 500662-B21 (#501536-001 is also equivalent)
Mfrs vary, Crucial, Hynix, Micron, & Samsung were all suppliers of these HP part #s.
(fwiw, I have 4GB OWC UDIMMs that carry the same Hynix part # as HP 4GB server memory!)
 
Hey is anyone experiencing this?
Installed 4 x
Micron MT36KSF2G72PZ-1G4E1HF 16GB 2RX4 PC3L-10600R HP PN 647653-081
Slots 1+2 & 5+6. Sometimes when i do a restart the Mac doesn't see 1 or 2 of the sticks. Sometimes it shows all 4.
If i do a cold startup it sees all 4. If i restart and jump around different OS versions it sometimes forgets there's ram in all the slots and shows 2 or 3 sticks instead of 4. Firmware version 141.0.0.0.0 and ECC status shows OK and Rember shows no errors. Tried cleaning out the contacts on both ends with rubbing alcohol.
What controls the memory check at reboot? Any help !?
 
Hey is anyone experiencing this?
Installed 4 x
Micron MT36KSF2G72PZ-1G4E1HF 16GB 2RX4 PC3L-10600R HP PN 647653-081
Slots 1+2 & 5+6. Sometimes when i do a restart the Mac doesn't see 1 or 2 of the sticks. Sometimes it shows all 4.
If i do a cold startup it sees all 4. If i restart and jump around different OS versions it sometimes forgets there's ram in all the slots and shows 2 or 3 sticks instead of 4. Firmware version 141.0.0.0.0 and ECC status shows OK and Rember shows no errors. Tried cleaning out the contacts on both ends with rubbing alcohol.
What controls the memory check at reboot? Any help !?

@tsialex could Vaz's bootrom be a good candidate for checking/removing the memory module data in the nvram which you recently reported on?
 
@tsialex could Vaz's bootrom be a good candidate for checking/removing the memory module data in the nvram which you recently reported on?
I already did a reconstruction for @VaZ, don't know if it's the same Mac.

A simple and easy test is to dump/backup the current SPI flash contents with ROMTool then flash the generic MP51.fd from 10.14.4 (141.0.0.0.0) and check if the same behaviour still happens. If stops, it's a NVRAM related problem and I'd like to take a look. If still happens, it's something else, probably a bad contact somewhere.
 
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Thanks i will try that tonight when i shut down to take a look at which chip to dump from behind the video card. Or will waiting for the final release 144 be a good test as well since it'll probably be released just around the corner !?
 
Thanks i will try that tonight when i shut down to take a look at which chip to dump from behind the video card. Or will waiting for the final release 144 be a good test as well since it'll probably be released just around the corner !?
Historically, 10.x.5 versions are released between the second half of May to the first week of June. I'd test this with 141.0.0.0.0 now.
 
Some time ago, I was trying to get 4x16GB working in my single processor (X5680 and X5690) Mac Pro 4,1 and 5,1 towers, with no success. I dropped the thread for a while, but decided to try again now that I've upgraded some of these systems to 140.0.0.0 and 141.0.0.0 firmware revisions. I'm happy to say that 64GB configs run just fine under the more recent firmware revisions, even if I revert back to maOS 10.12.6.

I haven't done any benchmarks to see how much RAM performance I'd give up with that configuration versus the 3x16GB triple channel config, but I'm glad it's now an option for me.
 
Thanks i will try that tonight when i shut down to take a look at which chip to dump from behind the video card. Or will waiting for the final release 144 be a good test as well since it'll probably be released just around the corner !?

So looks like i have 2 sticks of ram with poor contact points. That would explain the restarts failing to detect those 2 sticks most of the time. However if i seat and lean those 2 sticks towards the outside by 1mm since they wiggle a tiny bit, they seem to load up at reboot more often than not. They are server pulled sticks so i think they weren't handled with great care at one point. Going to replace them soon. Thanks again!
 
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 support up to 160GB memory (5x32)

**Currently there is NO confirmation if 32GB DIMMs can be used on a single processor cMP to further push up the memory size limit.**
I tested 32GB memory module as I wrote at page 4 of another thread https://forums.macrumors.com/thread...nyone-tried-this.2046693/page-4#post-27463869
Here is my test result:
macOS(OS X) 10.11 - 10.15 (does not support 32GB module)
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 support up to 128GB memory (8x16)
OS X Yosemite 10.10 (supports 32GB module with limitation)
A single W36xx CPU can support up to 56GB memory (3x16 + 8)
A single X56xx CPU can support up to 128GB memory (4x32)
A dual X56xx CPU can support up to 160GB memory (5x32)

Another detail is:
https://forums.macrumors.com/thread...nyone-tried-this.2046693/page-4#post-27465121
Here is the summary of my tests of 32GB modules on Mac Pro 2009 (MacPro5,1 BootROM: 144.0.0.0.0) for two days:
* CPU tray, Dual or Single, does not matter.
* W36xx cannot support 64GB or larger. Windows 10 (and MemTest86 V8.2) can use only 2GB.
* Windows 10 (and MemTest86 V8.2) can boot and use 32GB memory modules.
* OS X Yosemite 10.10.5 boots and uses 32GB modules up to 160GB. If exceeding 160GB, it does not boot.
* macOS (OS X) 10.11 - 10.13 ignores 32GB modules. If it has 16GB modules (maybe smaller module as well), macOS boots, but simply ignores 32GB modules.
* macOS Mojave 10.14 and Catalina 10.15 cannot boot if 32GB modules exist.
* 6 and 3 modules (192GB and 96GB) runs with 1066MHz.
* 8 and 4 modules (256GB and 128GB) runs with 800MHz.
 
Hi all,

I currently have a dual CPU (standard 2.26 to be upgraded to X5690/X5680) 4.1 upgraded to a 5.1?

Are either of this RAMs compatible?

16GB HP 500207-071 HYNIX 4Rx4 PC3-8500R registered ECC server RAM memory; https://www.ebay.co.uk/itm/16GB-HP-...407091?hash=item4d98d26533:g:dMoAAOSwwaNdOXE1

16GB SAMSUNG M393B2G70BH0-YH9 2Rx4 PC3L-10600R ECC server RAM memory; https://www.ebay.co.uk/itm/16GB-SAM...190483?hash=item4d971495d3:g:7eYAAOSwiiBc290X

If both are compatible is there any reason to pay extra for the Samsung?
 
Thanks thats the cheapest I have found for the Samsung, what price should I be aiming for?

I've seen lower than $15 USD per module when they are server pulls, but the prices do fluctuate. There's a newer listing on eBay for the same 2Rx4 Samsung modules I'm using at under $10/module for sets of 4x16GB (64GB total), but I'm sure that one will jump a little.

If you're buying multiples or eight total, it's really more important to make sure they match and would spend a little more to do so if necessary. You can mix certain modules, but it can be a bit of a mixed bag when taking those chances buying from multiple sellers.
 
I've seen lower than $15 USD per module when they are server pulls, but the prices do fluctuate. There's a newer listing on eBay for the same 2Rx4 Samsung modules I'm using at under $10/module for sets of 4x16GB (64GB total), but I'm sure that one will jump a little.

If you're buying multiples or eight total, it's really more important to make sure they match and would spend a little more to do so if necessary. You can mix certain modules, but it can be a bit of a mixed bag when taking those chances buying from multiple sellers.

I cant find any at price

The seller seems to have 3 models Im so confused now lol. All 3 are the same price

1. M393B2G70BH0-CK0 - PC3-12800 (DDR3-1600)
2. M393B2G70BH0-YH9 - PC3L-10600R (DDR3-1600)
3. M393B2G70DB0-YK0 - PC3L-12800R (DDR3-1600)
 
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I cant find any at price, What about these - Samsung M393B2G70BH0 16GB PC3-10600R Memory Kit

Suggest you search these part numbers on the forum before posting. That one specifically has reports of success from several users.
 
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