Mid 2009 Model A1278 / 2.26 or 2.53 GHz Core 2 Duo processor EMC 2326

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Problem with RAM Upgrade


I happened to have two 2GB RAM Chips from my new 2012 MacBook Pro (which was upgraded to 8GB) and wanted to use them to upgrade the older 2009 MacBook Pro, which runs with two 1GB Chips.

Unfortunately, the MacBook won't start after I have installed them. Back with the old Chips it is running fine again.

The specification of the two new Chips is 1Rx8 PC3-12800S-11-10-B2. The old Chips are already inside the Mac again, so i can't tell their specification right now, but it was obviously different.

Why shouldn't they work? Of course they are supposed to run with much faster FSB than the old ones, but running slower shouldn't matter? Or is there another difference in the specification?

Thanks for your help, the old MacBook would really like the Upgrade ;)

Answered! View the answer I have this problem too

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Unlike PCs, most Macs will only run correctly with the correct speed RAM. For your machine this is:

Supports 1066 MHz PC3-8500 DDR3 SDRAM.

This machine will support up to 8 GBs of RAM

To see what your machine has, go under the Apple to "about this Mac > more info > memory

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Oh, that's a pity. But thanks for your answer!


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You may also have DDR2 memory in the '09 whereas the 2012 will have DDR3.

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Sebastian will be eternally grateful.
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