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[SOLVED] 5.1 - Mid 2012 - 3.33 Hex - Memory Question

crjackson2134

crjackson2134

macrumors 601
Original poster
Mar 6, 2013
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Charlotte, NC
I was wondering if anyone can tell me about this memory.

Does it meet the qualifications for my system listed in the title and signature, and does anyone know if it has the thermal sensor chip?

Thanks...
 
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I have the same brand/spec of memory in my Dual 3.49 Hex 2010 MP (it was actually purchased from the same website) although mine are 6 sticks of 8GB. They work great.
 
Okay, so I decided to pull the trigger on 3 of them. I've heard there are specific ram slots to install them in for optimal performance due to the 3 channel controller. I've been told by others that the configuration that is shown in the little handbook that come with the MP are not the most optimal.

Can someone with experience tell me the best configurations for 3 sticks?
 
^^^^My understanding is that the receptacle closest to the heatsink should be left blank for best RAM performance. From what you have written I am assuming a 4 or 6 core machine.

Lou
 

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The idea is to populate memory channels for each CPU so that you end up using the same number of channels per CPU (i.e.: if you have three sticks of memory and two CPUs then you will not have an optimal configuration, on the other hand if you have two or four sticks or an even number in general then you can properly populate channels with one stick per CPU if you have two sticks or two sticks if you have four total)
 
More precisely, three sticks per CPU, since they are triple-channel. Two or four sticks per CPU create a dual-channel situation.

For triple channel operation -
Single CPU: three matched sticks
Dual CPU: six matched sticks, three on each side.

I care more about maximizing RAM, so I have four matched sticks of 8GB in my single CPU, which runs dual channel.
 
wonderspark said:
More precisely, three sticks per CPU, since they are triple-channel. Two or four sticks per CPU create a dual-channel situation.

For triple channel operation -
Single CPU: three matched sticks
Dual CPU: six matched sticks, three on each side.

I care more about maximizing RAM, so I have four matched sticks of 8GB in my single CPU, which runs dual channel.
Click to expand...

Okay, for my particular purpose, does the slot 1, 2, 3 (4 blank) get me the optimal configuration on the 3 memory channels? 16GB x 3
 
Okay, so I've ordered my 48 GB in 3x16GB sticks. A thought came to mind and I'm just wondering. If a Dual CPU system can support 128GB total then what prevents a Single CPU system from utilizing 64GB total?

Would 2 x 32 GB modules work in a single CPU system to provide 64GB of usable memory, or is there some other limitation?
 
crjackson2134 said:
If a Dual CPU system can support 128GB total then what prevents a Single CPU system from utilizing 64GB total?

Would 2 x 32 GB modules work in a single CPU system to provide 64GB of usable memory, or is there some other limitation?
Click to expand...
Current OS X versions up to 10.8.4 can only support 96GB, but the upcoming 10.9 will support 128GB. As for 32GB RAM modules currently available, they are all Load Reduced DIMMs and not compatible with the 2009-2012 MPs as explained in this post. That's why we don't see any Mac resellers such as OWC offering any 32GB modules. Here's a link explaining the new LR-DIMM in case anyone is interested.
 
xcodeSyn said:
Current OS X versions up to 10.8.4 can only support 96GB, but the upcoming 10.9 will support 128GB. As for 32GB RAM modules currently available, they are all Load Reduced DIMMs and not compatible with the 2009-2012 MPs as explained in this post. That's why we don't see any Mac resellers such as OWC offering any 32GB modules. Here's a link explaining the new LR-DIMM in case anyone is interested.
Click to expand...

Okay, cost aside... It looks to me like a single processor MP with 4 slots COULD theoretically go from the current maximum of 48GB to 64GB by replacing all the memory with 2x LR-DIMM 32GB PCS (when available). Am I missing something?

I'm not talking about mixing them, I'm not talking about pricing. I'm just asking if it's possible to stuff 64GB of working memory in the current MP Hex-Core machine when memory is available.
 
You can run 64GB of RAM in a single CPU Mac Pro, or 128GB RAM in a dual CPU Mac Pro today, but only if you boot into something other than OSX.

People running Windows on their Macs have been using all 128GB of RAM for a while now. Here's a thread discussing it. Perhaps when OSX 10.9 comes out, you can automagically use the extra RAM.
 
wonderspark said:
You can run 64GB of RAM in a single CPU Mac Pro, or 128GB RAM in a dual CPU Mac Pro today, but only if you boot into something other than OSX.

People running Windows on their Macs have been using all 128GB of RAM for a while now. Here's a thread discussing it. Perhaps when OSX 10.9 comes out, you can automagically use the extra RAM.
Click to expand...

I actually don't do windows and haven't for MANY years. I've used linux for a very long time. Before that OS/2, DOS, UNIX, CP/M, and various other OS's that are now defunct... I was aware of the 96GB limit on OSX, but I thought (for some reason) the 48GB limit on single CPU MP was a hardware limitation. If I'd known that I can put another 16GB stick in that empty slot (and use it in linux), I'd have ordered more memory a few days ago.

Although, I now plan to do some VMwindows once in a while when I'm feeling masochistic.
 
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spacedcadet said:
Next version of OSX finally supports maximum memory in dual processor models only.

http://macperformanceguide.com/blog/2013/20130611_9z-OSXMavericks-128GB-in-use.html
Click to expand...
Thanks for the link and I missed that the single-processor MP has a hardware limit of 48GB as OWC confirmed it:
Bad news on the 4/6-core from OWC:

Nope, still no go, can't even get the OS to load with 64GB in my 6-core.

Apparently a hardware limitation with the 4/6 core model processor tray/chipset
Click to expand...
I doubt that Apple would bother to make 32GB RAM module compatible with MP4,1 and 5,1, looks like 3x16GB is the top end for a single-processor MP.
 
xcodeSyn said:
Thanks for the link and I missed that the single-processor MP has a hardware limit of 48GB as OWC confirmed it:

I doubt that Apple would bother to make 32GB RAM module compatible with MP4,1 and 5,1, looks like 3x16GB is the top end for a single-processor MP.
Click to expand...

I don't think anyone ever thought that Apple themselves were going to become chip makers and offer a special solution. I'm not sure how that sneaked into the thread.

I just wanted to know if it was a hardware limitation that could be overcome by the introduction of the 32GB DDIMM modules. It seems no one (including OWC) has tried that particular configuration. I would have never considered it to be an OS limitation since we already knew Linux can address 128GB on a dual core MP.

I guess I'll have to wait until someone try's to get the answer.
 
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