6 or 8 DIMMS in 2010 Mac Pro Dual Processor?

Hi Trailerman,

You are correct in your understanding that the 2009 and 2010 Mac pros use a triple channel memory controller - memory slots 3&4 and 7&8 share the same channel.

However, in general there is only a very small decrease in performance using all 8 memory slots:
http://macperformanceguide.com/Reviews-MacProWestmere-Memory.html

A few applications, Photoshop CS5 in particular, will use all the available memory up to the maximum 64GB, but I am not familiar with Logic Pro or any audio software, because I use my system mainly for photo editing, digital imaging and colour printing up to A2 size.

If all the memory modules you install are 1333MHz, then your memory speed will not drop to 1066 MHz.

In my opinion you cannot have too much memory, but obviously cost is a major factor. If you start off with however many 8GB modules (in pairs) are within your budget now, then you can always add more (in pairs) in the future.

If I could afford to, I would upgrade to 64GB RAM, purely for Photoshop CS5, but when I upgraded from the original 6GB of Apple RAM, in November 2009, 2GB was the largest capacity sold by Kingston, and there was a lot of negative feedback at that time about the recently introduced 4GB modules from OWC and Crucial - in fact the latter's 4GB modules were still incompatible with some Mac pros as recently as a couple of months ago.

However, I find that 16GB (8 x 2GB Kingston RAM) is more than adequate for my general requirements.

From personal experience I can thoroughly recommend the Kingston brand, but at the moment they do not sell anything larger than 4GB modules, and so, if you decide to max out your memory, then I would recommend importing 8GB DIMMs from OWC.

I have used OWC on a couple of occasions, and both times I received the goods within 2 days via Federal Express, who then invoiced me for the VAT element plus a £10.00 Advancement Fee.

Lloyd Chambers' Mac Performance Guide is biased towards photography, and includes only a limited performance guide with Apple Logic Studio:
http://macperformanceguide.com/Reviews-MacProWestmere-LogicStudio.html

Possibly you are already aware of this website, but I will include it just in case you are not, because it has 50 pages of feedback from Logic users:
http://www.gearslutz.com/board/music-computers/371545-logic-pro-multicore-benchm arktest.html

Hope this helps,

Regards,

Bill

In my opinion you cannot have too much memory, but obviously cost is a major factor. If you start off with however many 8GB modules (in pairs) are within your budget now, then you can always add more (in pairs) in the future.

I do not think pairs are needed for a Mac Pro 2009 and later.

What you do need to consider is that most 8GB DIMMs do not play nice with any other sizes, so making the jump to any 8GB DIMMs requires you to dump all your smaller DIMMs. So if you think you will EVER move to 8GB DIMMs, the suggestion is to make that leap immediately, but install fewer than the optimum three modules. Mac Performance guide (cited above) says the real-world penalty for two modules instead of the optimum three is under 4 percent, and the penalty for four is even smaller.

Hi Jules,

I think you have made the right decision going for 32GB RAM instead of 24GB.

However, it's a shame that you had already ordered your original 6 x 4GB from Crucial, instead of buying the Kingston brand, because, as I stated in my earlier post "their 4GB modules were still incompatible with some Mac Pros as recently as a couple of months ago".

See:
http://discussions.apple.com/message.jspa?messageID=12586929#12586929

Hopefully their 1333MHz modules for the Westmere Mac Pro are better than their 1066MHZ ones for the Nehalem Mac Pro, but only time will tell.

Best of luck!

Bill

PS

The reason I always recommend the Kingston brand is that their "System Specific" memory for Mac Pros is made to Apple specifications, including thermal sensors.

I have yet to find anything on either the UK or USA Crucial websites stating that their modules for 2009/2010 Mac Pros have thermal sensors, which possibly means that they do not.

Message was edited by: Biltan-Wales

Hi Grant,

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I do not think pairs are needed for a Mac Pro 2009 and later.
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I was recommending OWC 8GB modules and I quote from their website:
"*8GB Module sets require that all installed modules be of the same kind OWC 8GB module".

As Jules has a 12-Core Mac Pro, which has a total of 8 memory slots (4 for each processor), that is why I recommended buying 8GB modules in pairs.

So one pair would be installed in memory slots 1&5, and any additional pairs in 2&6, 3&7, 4&8.

Hope that clarifies what I was trying to get across.

Regards,

Bill