Secret Firmware Update Lets Late \'08 MacBooks Use 8GB of RAM

Secret Firmware Update Lets Late \'08 MacBooks Use 8GB of RAM

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OWC has discovered that a 'secret' firmware update has enabled access to 8GB of RAM on late '08 MacBooks.

In late 2009, an EFI Firmware Update was released to address the buzzing noises coming from the optical drive. However, it seems that somewhere along the line, Apple changed this update without notating it anywhere.

Whether any other elements were affected by this change is undetermined, but it did change memory addressing; with the later version of the update installed, you could address a full 8GB in Snow Leopard. Unfortunately, Software Update doesn’t show this version as being different from the previous one, so users wouldn’t be notified if they had already updated their firmware to the older version.


This discovery applies to the following MacBook models:
● MacBook 13.3" 2.0GHz and 2.4GHz
● MacBook Pro 15" 2.4GHz (All)
● MacBook Pro 15" 2.53GHz model w/ExpressCard Slot (Late 2008)
● MacBook Pro 15" 2.8GHz model w/ExpressCard Slot (Late 2008)

Check your BootROM version in System Profiler and make sure its MBP51.007E.B05 for MacBook Pros and MB51.007D.B03 for MacBooks.

If your BootROM doesn't make the numbers above, download and install the "secretly" updated firmware from here:
● MacBook Pros (MacBookPro5,1): MacBook Pro EFI Firmware Update 1.8
● MacBooks (MacBook5,1): MacBook EFI Firmware Update 1.4

Finally, make sure you are on Snow Leopard 10.6.6 then upgrade your RAM to 8GB. I'll be doing this first thing tomorrow morning!

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Secret Firmware Update Lets Late \'08 MacBooks Use 8GB of RAM

Daniel - March 7, 2011 at 1:37pm
Saw this post today. Im currently running 2x2GB DDR2 (4 GB total) on my Old Mac Book Pro Core 2 Duo (Silver Keys). Wont let me do the update as it says i dont need it. My bootroom version is MBP41.00C1.B03. So i went to my local computer store today and figured it try my luck...they only had one one 4gb DDR2 chip in stock so i bought it anyways and ordered the second to arrive next week sometime....Happy to say I just put the one 4gb chip along with one of my old 2gb for a total of 6gb and System Profiler is recognizing all 6gb no problem!!!! Computer is considerably faster. Will keep you all posted when i drop the other 4gb in next week for a total of 8!!! YEEEEHAAAAA!!!!
Daniel - March 7, 2011 at 3:10pm
Ok...update....just had my first crash....screen and mouse froze after about two hours of running normally, browsing, watching videos, music, etc. The computer also got quite hot just before the crash so im guessing the processors were working their asses off.... Restarted the computer and everything is fine again. Im guessing the RAM did it but not sure.
Khan - March 7, 2011 at 8:21am
Guys I have MB51.007D.B03 Can i get 8 GB RAM on my MacBook?
khan - March 7, 2011 at 8:27am
My MB is 2.0GHz
Gustavo Albornoz - March 6, 2011 at 1:41pm
Please, a tutorial would be great, I\'m trying to update, but i\'m getting a message,\"this computer does not need this update\"
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