‘Only’ 8Gb of RAM in a 2009 Mac Pro

Is it just me or does anyone else think that the 8Gb RAM limit on the new Quad-Core 2009 Mac Pro is a bit of a retrograde step? I keep reading reviews saying what a wonderful machine this is, how fast it is, how easy it is to upgrade the RAM etc, but no-one seems to mention the glass ceiling at 8Gb?

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I have an early 2008 Mac Pro, or a Gen 2 Mac Pro – whatever you want to call it. It’s the single 2.8GHz Quad-Core Intel Xeon version and it currently has 12Gb of 800MHz DDR2 memory fitted. Yep, that’s twelve gig… and I use it. I work from home for a large part of the time, and part of my work involves supporting a variety of large corporate customers. For this I remotely access their systems using dedicated Windows XP clients which I run under VMware Fusion 2.x. Each virtual client machine has around 12Gb of hard disk space and 2Gb of RAM allocated to it, and with my current configuration I can run up four virtual machines simultaneously and get good performance out of each virtual machine, while at the same time run a pretty snappy OS X desktop for all my personal stuff. The ability to run multiple VMs at the same time and not have the whole thing slow down and start swapping is an absolute godsend, and I even run up a virtual Windows server at times for good measure.

So in the eyes of Apple, what would be my upgrade path? The new Quad-Core Mac Pro tops out at just 8Gb of RAM. Ok it has more grunt in the CPU department, but the 8Gb memory limit rules it out, and would require me to drop a whopping three grand or so on a new Eight-Core kitted out with 12Gb of RAM (obviously I wouldn’t be paying Apple’s silly prices for RAM).

I understand the 8Gb limit may be some sort of architectural limitation, but it does throw a spanner in the works when it comes to possible future upgrades. As it happens, the 2008 Mac Pro is a fantastic machine for running multiple RAM hungry Windows VMs, and unless I’m next in line for that big win on the lottery then this current machine is going to be my best option for quite a while yet. I have heard rumours that the 2009 Quad-Core will ‘unofficially’ support more than 8Gb of RAM, but I’ve yet to chase down some definitive answers.

Here’s a list of some interesting snippets I have come across. Not sure if there’s any truth in them but here goes anyway. (I’ll add to this list as I find more):

  • Optimal memory configuration in the 2009 Mac Pro is three matched DIMMs, so 3 x 2Gb would be better than 4 x 2Gb.
  • The limit has nothing to do with the architecture of the Nehalem processor, it’s artificially imposed by Apple as part of the EFI BIOS settings.
  • Someone somewhere has added 4 x 4Gb sticks in to their 2009 Quad-Core, and it ‘works’.
  • Apple doesn’t officially support 4Gb DIMMs in the 2009 Quad-Core.

By the way, have you seen the list price of eight 1066MHz DDR3 4Gb DIMMs from Apple? How does £4,880 (+ VAT) sound??!

That's something a 2009 Quad-Core Mac Pro can't "officially" do.

That's something a 2009 Quad-Core Mac Pro can't "officially" do.