I've got a Mac Pro (early 2009), 2.66 GHz Quad Core Intel Xeon. I currently have 3GB of memory (three 1GB modules) and need to increase that. I may purchase a 4GB module (if I can't find any 2GB ones online), and my question is: will a 4GB module in my Mac, sharing space with the three 1GB modules, work okay? Thanks.
You might look at some of the sites such as OWC or Crucial
http://eshop.macsales.com/MyOWC/
find your model and see their recommendations
If an 8GB module is less than twice the price of a 4GB module, it is more economical to buy the 8GB instead, and leaves slots open for future expansion.
Do not buy 16GB modules, and they are ALL "Registered" DIMMs and will not mix freely and play nice with non-registered DIMMs, Regardless, when the new DIMMs arrive, test the new ones by themselves FIRST, then add the old ones back and test again. This separates "does not work" problems from "will not play nice with others" problems.
always buy from a Vendor who says:
"It works in your Mac
or your money Back!"
I would add datamemorysystems to that list:
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What memory module do I buy?
