RAM / MacPro4.1 Single Processor 2.93 GHz not listed in Tec Specs

You can install up to 6 GBs or RAM. It uses:

2 - 200-pin PC2-5300 (667MHz) DDR2 SO-DIMM.

This would be your Tech Specs page. It covers all models, both single and dual processor:

Mac Pro (Early 2009) - Technical Specifications

You can do the large amount of research needed to develop the expertise to specify your memories, but most users buy from a vendor that knows Macs, and can tell them what memories will work in their Mac. A Money-back guarantee ensures the the vendor sends you the correct memories.

Lifetime Warranty is also standard. This encourages Vendors to sell only the highest quality DIMMs.

Your Mac can use up to 8GB DIMMs, but Apple does not yet support 8GB DIMMs. That makes it even more important to buy from a Vendor that will support what they sell.

In the US, 8GB DIMMs are being sold by:
Macsales.com (Other World Computing)
DataMemorySystems.com
MemorytoGo.com
RAMJet.com
TransIntl.com

Crucial is sometimes listed as a vendor on search sites, but they are not yet ready to ship AND SUPPORT these denser DIMMs at this writing.

Availability of 8GB DIMMs in Europe still appears to be a problem.

That is not the right spec for the 2009 MAC PRO model, which I own, and self-identifies as MacPro 4.1. The Apple Spec and Apple System Profiler Spec list:

1066MHz DDR3 ECC SDRAM

I think you may be listing the Spec for the MacBOOK Pro.

If you prefer to have one single source for your computer and everything in it, you can get Apple RAM (installed by Apple) for the price listed. Some users get tremendous piece of mind knowing that their Mac is all Apple, and that there will be no controversy ("Oh, the problem is caused by your non-Apple RAM!") if there is a problem.

Users who are handy and can do their own memory upgrades without damaging their Macs may choose to save money by buying RAM from Third parties and installing it themselves.

If you follow the rules I suggested above, you will get high quality RAM that works the first time, every time, and if it fails, the Vendor will replace it:

• A vendor that knows Macs, and tells YOU what memory you should use
• Money-back guarantee if they send you RAM that does not work for ANY reason
• Lifetime Warranty

Most of the discussion on this issue surrounds the 8GB DIMMs, but would also apply to 4GB DIMMs.

At this time, most 8GB DIMMs do not work when any other sized DIMMs are installed in the machine. If you think you may want to expand beyond 16GB total, at some point you will have to throw away the 4GB DIMMs and switch over to 8GB DIMMs. That is an expensive proposition.

Three modules is optimum. Memory-tester programs that thump on the memories non-stop show that there is a penalty for using only two modules, and also a penalty for using four modules. But if you test with real-world Applications, you find that the penalty for using two or four modules is under five percent.

So users contemplating > 16GB memory can install two 8GB DIMMs today with under a five percent speed penalty, and add one later and go faster. If they ever need the fourth one, the increase in overall System performance will more than offset the last five percent penalty for adding the fourth module.

If you go beyond the limits Apple has specified, you will need support from someone. Users who have bought larger modules from reputable vendors -- who know and support Macs -- have been satisfied with the results.

It would be a mistake to go to the electronics store and just buy the 8GB DIMMs you think you need with no guaranties. Who will answer any questions or problems that come up? What if they do not work for you?

The 4,1 model is a 2008, not 2009, model according to the information I have. There is a late 2008 model that is identified as 5,1, but the 4,1 has different specifications for memory. Check MacTracker and Everymac.com, which is what I did.

esa ceduti wrote:
yet considering the balance issue, it would be 3x4, or 2x8+2x4… which is a bit expensive indeed.
You know anything specific about the upper limit question? (2x8+2x4 exceeds the 16G specified by apple, and I know nothing but macsales claim.)

The issue is memory ranking - 4GB DIMMs - at least the ones from Apple are typically dual ranked. The only 8GB DIMMs I am aware of are quad ranked. You can not mix rankings within the same memory bank. There are quad ranked 4GB DIMMs out there, but honestly you would just be better off with the 8's.