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Mac Pro 5.1 RAM Upgrade

E

Ethosik

Contributor
Original poster
Oct 21, 2009
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I am having trouble finding the perfect RAM to use to upgrade my 8GB. I have a 2010 Mac Pro 5.1 single 6-core with only 8GB of ram.

1) What is the maximum amount of ram the single processor can have? 32GB?
2) What is the best (I do not care about expense) ram to use for the upgrade to the max?

I looked at Newegg and OWC. I just am not sure what to get and some of the ram on Newegg has bad ratings.
 
1) 48G (3x16G) for best performance, or absolute max is 56G (3x16G + 8G) at this moment.

2) I think most 1333MHz CL9 ECC UDIMM should works well with your 5,1, but I really don't know which one is the best. Anyway, 3x16G is the best option for single CPU Hex 5,1.
 
I have used Data Memory Systems since I started using a Macintosh, back in 1986. It carries a Lifetime Warranty. I have never received a bad stock of RAM from those guys.

http://www.datamemorysystems.com/ap...33ghz-mc560ll/a-cto-mid-2010-memory-upgrades/

As far is Max RAM is concerned the above post has it spot on.

The CPU in you machine has three channel memory, and populating the first three slots (leaving slot 4 MT) with equalized DIMMs produces the best performance.

Lou
 
flowrider said:
I have used Data Memory Systems since I started using a Macintosh, back in 1986. It carries a Lifetime Warranty. I have never received a bad stock of RAM from those guys.

http://www.datamemorysystems.com/ap...33ghz-mc560ll/a-cto-mid-2010-memory-upgrades/

As far is Max RAM is concerned the above post has it spot on.

The CPU in you machine has three channel memory, and populating the first three slots (leaving slot 4 MT) with equalized DIMMs produces the best performance.

Lou
Click to expand...

Are the slots labeled? Is the first slot closer to the CPU, or closer to the case door?
 
^^^^They are marked, but for clarification see attached.

Lou
 

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^^^^Again, I can only go from experience. I have never used any other brand of RAM, since I have been happy with DMS. I also like their sales staff, if any issue arise they will go out of their way to help.

Lou
 
Thanks. Since I will be getting 4 sticks instead of 3, how will that affect my performance? I am assuming since it is triple channel that three sticks are better, but how much do I lose having 4 sticks? I already have 4x2GB sticks for 8GB of memory.
 
you won't notice any difference if you go with four DIMMs. but it will show if you run benchmarks (I tested it with geekbench). AFAIR the difference was roughly 10 or 15%.
 
mikeboss said:
you won't notice any difference if you go with four DIMMs. but it will show if you run benchmarks (I tested it with geekbench). AFAIR the difference was roughly 10 or 15%.
Click to expand...

So since I already use 4 DIMMS (4x2GB for 8GB), I won't get any performance changes? I am fine with that. This is just temporary anyway. I will probably get 3x16GB next year.
 
yep, performance should be the same as before. and if you really want to know I suggest that you run geekbench. this specifically benchmarks memory performance (and CPU, of course).
 
So when I installed the RAM, all four modules, it only detected 16GB of ram instead of 32GB. When I turned the system off and took all modules out and reseated them, I restarted and it only detected 24GB and there was a red light by slot 1. I took the module from slot 4 and replaced it with the module on slot 1 (keeping the old module that was in slot one out). It detected 24GB of ram which was good, I only had three modules installed. Finally, when I put the last module back in and started my system, all 32GB of ram was detected.

Does anybody know why this happened?
 
Mac Pro is configured for 1.5 Volt Memory

Mac Pro is configured for 1.5 Volt Memory

You should be aware that most of the new 16 GB DIMMs are 1.35 V (low-voltage DDR3). The motherboard of the Mac Pro (4,1/5,1) is configured for 1.5 Volt memory.

Nevertheless, I suppose Low Voltage memory should work in Mac Pro 4.1/5,1.

However, i would prefer 1.5 V DDR3 memory.

http://superuser.com/questions/564175/1-35-v-ram-in-a-1-5-v-system-will-it-fry-or-overclock
I quote: DDR3L (low-voltage DDR3) is just an "extension" of the DDR3 standard, so companies has to be aware that plugging a module will default to 1.5V on most systems. At 1.5V, the worst that will happen will be a waste of electricity/battery.
RAM modules contain pre-defined configurations (SPD, XMP, etc.) but the default one is often safer value that will work on as many systems as possible. For compatibility purposes, that setting might not be factory-set to 1.35V, but 1.5V instead. The default timings can also be different and slower from the ones indicated on your module package (I have an other answer on this topic).
For this reason, there's no chance it will overclock by itself even if it's running at a higher voltage (unless your current BIOS settings are manually set to run at specific speeds higher than your new modules would support - if so, reset your memory settings to AUTO before installing them).
If your RAM contains a XMP profile, try that as it can be factory set to 1.35 and all ideal settings - but you still have to select it manually in the BIOS.
In conclusion, 1.35V is perfectly safe. It's still always a good idea after installing RAM to go in the BIOS and verify/adjust the settings to ensure they match the module packages and perform optimally.
 
^^^^Thanks for your input. The 8GB DIMMsthat OP has and the 16GB DIMMs that DMS carries are indeed 1.5v.

Lou
 

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Synchro3 said:
You should be aware that most of the new 16 GB DIMMs are 1.35 V (low-voltage DDR3). The motherboard of the Mac Pro (4,1/5,1) is configured for 1.5 Volt memory.
Click to expand...


Doesn't matter. If it would be 1.35V, it would matter.
I use 3x 16GB PC3L modules in mine without problems. You can even mix 1.35V ones with 1.5V and it works as it should. Did it many times. Main difference between these two is that 1.35V can run @1.5V, but 1.5V ones can't run @1.35V.
 
666sheep said:
Doesn't matter. If it would be 1.35V, it would matter.
I use 3x 16GB PC3L modules in mine without problems. You can even mix 1.35V ones with 1.5V and it works as it should. Did it many times. Main difference between these two is that 1.35V can run @1.5V, but 1.5V ones can't run @1.35V.
Click to expand...

Thanks for info!
 
It does matter

666sheep said:
Doesn't matter. If it would be 1.35V, it would matter.
I use 3x 16GB PC3L modules in mine without problems. You can even mix 1.35V ones with 1.5V and it works as it should. Did it many times. Main difference between these two is that 1.35V can run @1.5V, but 1.5V ones can't run @1.35V.
Click to expand...

Since I tried. Never mix 1.35v with 1.5v, it's a bad idea. Mine gave Red LED on board.

Second, 1.35v sticks in MacPro 5.1 will automatically lower its frequency, ie from1333 to 1066mhz. I mentioned that in my other threads.

Mac pro 4.1/5.1 is for 1.5V. This is correct and as others said, make it right in one shot!!
 
Prince134 said:
Since I tried. Never mix 1.35v with 1.5v, it's a bad idea. Mine gave Red LED on board.
Click to expand...

Mine didn't. Few sets of mixed 1.35V still runs in few machines I built. No downclock as well. I didn't make this up, believe me or not.

Edit: after a bit of thinking, symptoms you described could happen when you mix differently ranked modules (red led) i.e. 2R + 4R for example. Downclocking occurs when you fill all banks with quad ranked sticks. Never happened to me with 2R sticks, regardless of the voltage.
 
Last edited:
So does anybody know what happened when I installed the memory? Everything is still working fine after the initial problems. I got the same modules from the same company, so there was no mixing going on.
 
^^^^Can't really answer your question, but I'm assuming it had something to do with the shared slots for the third memory channel. IMHO, Apple should have just used three memory slots for this iteration of the Mac Pro since the CPU supports 3 memory channels. Now that you have it working properly NJOY!

Lou
 
xWhiplash said:
I am having trouble finding the perfect RAM to use to upgrade my 8GB. I have a 2010 Mac Pro 5.1 single 6-core with only 8GB of ram.

1) What is the maximum amount of ram the single processor can have? 32GB?
2) What is the best (I do not care about expense) ram to use for the upgrade to the max?

I looked at Newegg and OWC. I just am not sure what to get and some of the ram on Newegg has bad ratings.
Click to expand...


HI,

You can look through the post #8 as linked below, and others in the same thread. I think you will get better picture. Basically 48GB is the max for your 6 core MP. As toward the 1.35v and 1.5V, my conclusion was staying 1.5V, since I paid a cost to that specific issue.

https://forums.macrumors.com/threads/1732968/

----------
666sheep said:
Mine didn't. Few sets of mixed 1.35V still runs in few machines I built. No downclock as well. I didn't make this up, believe me or not.

Edit: after a bit of thinking, symptoms you described could happen when you mix differently ranked modules (red led) i.e. 2R + 4R for example. Downclocking occurs when you fill all banks with quad ranked sticks. Never happened to me with 2R sticks, regardless of the voltage.
Click to expand...

I just talk about my own experience. As soon as I got problems mixing 1.35v with 1.5b, I quickly switched to all 1.5V sticks and it got cured. However, I can't rule out what you said....

From the other thread, the Kingston 16GB works for me.
https://forums.macrumors.com/threads/1732968/
 
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