Why does Apple only approve of up to 16GB RAM in 2009 Mac Pro?

[Luba]

Why does Apple only approve of up to 16GB (4 x 4GB) RAM in 2009 Mac Pro? I have a 2.66 Ghz Quad-Core 2009 Mac Pro, which I believe is a 4,1

4GB RAM module is the sweet spot value-wise, but I am considering getting 8GB modules . . . 3 x 8GB = 24GB, which also maintains triple channel memory access.

So I'll buy either 4 x 4GB = 16GB or 3 x 8GB = 24GB for using Final Cut Pro X, Motion, CS5 Master Collection (thinking about getting CS6) and playing around with DaVinice Resolve. Which would you recommend, 16 or 24?

Also part of the decision process is possibly buying a new Mac Pro down the road in 6 months, if it comes out and the price and upgrades are worth it.

Thanks for any feedback.

 

[GGJstudios]

Why does Apple only approve of up to 16GB (4 x 4GB) RAM in 2009 Mac Pro?

Apple has historically been conservative when stating maximum RAM. You can find specs on all Apple products, including maximum RAM:

• By visiting EveryMac.com: Actual Maximum RAM
• By selecting your model on the Crucial Memory Advisor™ Tool to find RAM information
• By using Mactracker
• By entering your serial number here to find specs for your model.
  (Be aware that some models can use more RAM than Apple shows. Check EveryMac to verify actual usable RAM.)

 

[Umbongo]

Because they only supported ECC Unbuffered DDR3 PC3-8500 DIMMs and there were no unbuffered 8GB DIMMs available until 2011. This was still the case with the 2010 models, now on PC3-10600, at the time of launch. See the manual entry here: http://i47.tinypic.com/29fur6v.png

It all comes down to only wanting to offer type and one speed of memory for simplicities sake (and lowering Apple's costs). Also note that Intel did not support Registered DIMMs on the single socket Xeon processors, although they did work. This meant no vendors offered RDIMMs with Xeon 3500 and 3600 series processors. Apple were the only one to eventually do so. This has since changed with the introduction of the E5-1600 series.

Later Apple updated the 2010 model support to 8GB RDIMMs, because UDIMMs were still not available and they saw an opportunity to considerably increase profit on Mac Pro sales . No reason to update the 2009 support though as they didn't sell them any more with such an option. http://support.apple.com/kb/HT4584

 

[deconstruct60]

Apple has historically been conservative when stating maximum RAM.
....
(Be aware that some models can use more RAM than Apple shows. Check EveryMac to verify actual usable RAM.)[/list]

But some of those solutions involve using only matching solutions. They may not mix-and-match with Apple DIMMs. Usually it isn't a problem though retiring all of Apple's much smaller DIMMs though for more cost effective 3rd party ones.