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1333Mhz ram in 1066 MacBook Pro

I have a MacBook pro (specs below) which specifies DDR3-1066 memory. I ordered an upgrade kit from Ramjet to go from 2GB to 8GB. Installed two 4GB modules and everything seems to be fine. However, after checking "About This Mac" I find that the installed ram is 1333, not 1066. They apparently shipped the wrong thing.


As I said, everything seems fine, despite warnings I've seen here. Has anyone had long-term experience with 1333 ram in a machine with a 1066 bus? Should I cross my fingers and keep going or return them and get 1066 modules?


Model Identifier: MacBookPro5,1

Processor Name: Intel Core 2 Duo

Processor Speed: 2.4 GHz

Number of Processors: 1

Total Number of Cores: 2

L2 Cache: 3 MB

Memory: 8 GB

Bus Speed: 1.07 GHz

Boot ROM Version: MBP51.007E.B05

SMC Version (system): 1.41f2

MacBook Pro, Mac OS X (10.6.8)

Posted on Sep 18, 2011 8:24 AM

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19 replies

Sep 19, 2011 7:11 AM in response to Rick Feldkamp

?? You've now been told twice that your 1333 ram is not running at 1333. Why are you saying it "IS" working? It is is falling back to your bus speed. It is not working as designed, i.e. 1333. It may continue to fall back or one day it may just fail to work. As I previously said, you should use the ram designed for your computer.


BTW and FWIW, I changed out my ram so I think I am "someone with actual experience".

Sep 19, 2011 9:15 AM in response to Csound1

You are correct, ram should be, usually is, backward compatible to run at slower bus speeds. But because something should be or usually is, does not convince me to not use the memory specified for my computer.


I know the faster ram will run, but not at its full capability speed. My approach every time, and I've done it many times, is to use the ram specified for my computer. If the OP wants to use faster ram that is fine.


Here is another thread about the topic: https://discussions.apple.com/thread/3029172

Sep 19, 2011 2:33 PM in response to BobTheFisherman

BobTheFisherman wrote:


You are correct, ram should be, usually is, backward compatible to run at slower bus speeds. But because something should be or usually is, does not convince me to not use the memory specified for my computer.


I know the faster ram will run, but not at its full capability speed. My approach every time, and I've done it many times, is to use the ram specified for my computer. If the OP wants to use faster ram that is fine.


Here is another thread about the topic: https://discussions.apple.com/thread/3029172

Better safe than sorry 🙂


Nothing wrong with that.

Jan 14, 2012 3:02 PM in response to BobTheFisherman

This may be a little late, but since I tried this just a few days ago:


I had a 2GB stick of 1333 RAM lying around, so I tried upgrading my A1278 Macbook Aluminum (late 2008, 1066 RAM). It didn't work if I attempted to combine it with either of the existing 1066 sticks, in either slot: The machine wouldn't power up at all. But the system booted normally if I removed all 1066 sticks, and booted with the 1333 stick independently. All major system functions seemed to behave as normal.


I suspect there's a timing issue involved with downcycling 1333 RAM to work at 1066 speeds. Maybe if the logic board is handling that issue for one stick, it can't dedicate the correct resources to the other stick. The next time I have reason to buy two 1333 SO-DIMMs, I'll try putting both in the 1066 machine and see if that works. That could be sooner rather than later, if I win an eBay auction for a 2011 MBP carcass and I'm able to get the logic board cleaned and working...

Jan 12, 2013 9:48 PM in response to Rick Feldkamp

I just got a mac mini to try and run through my macbook (have a post up looking for help with this) but without previously setting up the mini I can't vnc, remote view/control, or anything until I get access to a monitor or maybe just a keyboard... What I'm trying to get at is, the store I purchased the mini from didn't charge me for all the ram I got, I got two 4g sticks instead of 2 more 2g sticks (to match what was in the machine), thus I now have extra ram which led me to this same question/post and am feeling comfortable enough after reading this to go ahead with the 1333 install. Late '08 macbook so it's 1067 and hopefully all will go well, if not I'll be back asking, so thanks in a possible future!

Feb 23, 2013 4:49 PM in response to Rick Feldkamp

I ran 2x4GB Samsung 2RX8 PC3-10600S DDR3 SODIM (1333 MHz) ram on my mid 2009 MBP for 2 years. I bought it and had it installed at a small computer shop before I'd ever looked into anything about ram.


The computer ran very well (night and day compared to the 2GB I bought it with). I used office applications in both OSX and Windows (bootcamp), but mainly ran in Windows for my work. Nothing graphics intensive, except maybe google earth...


In late 2011, I downloaded a google earth upgrade. The new google earth looked more fancy, but would crash after about 20 seconds every time I opened it. I stopped using google earth.


I recently cleared my drive (incidental), installed Snow Leopard from scratch, and found that google earth was still unusable. I recently swapped the Samsung ram with two 4GB 1066 Kingston chips, "Specific Memory for Apple (KTA-MB1066K2/8G)". I'd researched and purchased the chips (after my upgrade) for my wife's Macbook, and she now has a new computer. Google earth now works great.


Now that I know, I wouldn never buy overclocked ram again. However if I had 8GB of 1333 lying around and only 2GB of 1066 in my 2009 MBP, I would certainly run the overclocked 8GB and deal with the occasional bugs.

1333Mhz ram in 1066 MacBook Pro

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