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I am looking at getting a dual Nehalem Mac Pro and i am wanting a bit more memory than the standard 6gb.

I am just wanting to know if there are any are any issues with the following memory configurations.

  • 6x 1gb + 2x 2gb giving 10gb in total (Suggested by the Mac sales person) - Cheapest
  • 4x 2gb giving 8gb in total
  • 6x 2gb - A lot more expensive

Searching around on the net it says it is optimal to run in multiples 3 and to have all of the dimms the same size. I was just wanting to know if the difference would be noticeable not doing this.

I will be using this Mac to do iPhone development and I will be running a few Virtual Machines with SQL Server, IIS, and Visual Studio on them.

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up vote 1 down vote accepted

With Nehalem DDR3 based systems that have the Northbridge integrated into the processor module, your 'best-bet' is usually with the three module DDR3 memory set (just like the older 2 matched module DDR2 memory advantages).

however, if you ask about perceivable differences,
given normal applications (which I agree is a subjective phrase),
I think the amount of memory will really rule your feel of the machine
rather than slight differences between matched and unmatched modules.

Suggest you read up some other questions tagged ddr3 and nehalem.

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Standard Memory: 6 GB (Removable)

Maximum Memory: 32 GB

Expansion: 8 Sockets (4 sockets per processor)

CPU & ChipSet: Intel Xeon 2.26 GHz
Intel Xeon 2.66 GHz
Intel Xeon 2.93 GHz

Bus Architecture: (N/A)

Mfgr's System P/N's: MB535LL/A; MB535T/A; MB535X/A

Comments This system supports triple channel mode when three identical modules are installed per processor. Kingston offers K3 kits to optimize performance and K4 kits to achieve maximum configurations. When using two processors (Mac Pro 8-Core) kits must be installed IN PAIRS.

Capacity Part Number Qty 6GB STD 8GB KTA-MP1066/1G 2 12GB** KTA-MP1066K3/6G 2 16GB** KTA-MP1066K4/8G 2 32GB** KTA-MP1066K4/16G 2

** Requires replacement of all standard memory where indicated.

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Overall you want the most memory using the least modules. The more modules in use the more strain on the northbridge, and the more points of failure you have. You want to have the least points of failure possible, and choosing less DIMMs with higher capacities gives you room to easily upgrade in the future, rather than scrapping all the current DIMMs and buying larger ones anyway.

I'd go for the 2GB modules, 6GB should be fine for your personal use unless you plan on hosting live high traffic sites.

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Being a dual cpu system that prefers matched triples, the 6x 2gb (3 for each cpu) would be the one that makes logical, if not financial sense. – dlamblin Nov 12 '09 at 4:22
whoops good catch – John T Nov 12 '09 at 4:36

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