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Hardmac.com
8 GB of RAM in a 2008 Macbook Pro
OWC made a very interesting discovery on the 2008 Macbook (and) Pro. These laptops were thought, and it was shown in tests, to be able to work with up to 6 GB of RAM but no more. However, it was discovered that some of them were able to fully use 8 GB of RAM. It appears that they all have in common an update EFI to modify the behavior of the Superdrive (to reduce the noise at start-up), which was released in 2009, but all the laptops that got that update do not support 8 GB of RAM. In fact, it appears that there were two updates and that the second one replaced the first without any warning and for people who had already updated, the second one didn't appear in the Software Update menu.
The following models are concerned:
13" MacBook UNibody 2.0GHz et 2.4GHz
All 15" MacBook Pro 2.4GHz
All late 2008 15" MacBook Pro 2.53GHz with Express Card
All late 2008 15" MacBook Pro 2.8GHz with Express Card
To support 8GB of RAM, the ID and Boot Rom have to be respectively MacBookPro5,1 and MBP51.007E.B05 or MacBook5,1 and MB51.007D.B03.
If you have a more recent Boot Rom, it is not a problem. Otherwise, you need to do the EFI update again manually, depending on the model, MacBook Pro EFI Firmware Update 1.8, or MacBook EFI Firmware Update 1.4.
After that, if you are running Snow Leopard 10.6.6, you will be able to put 8GB of RAM in your laptop and fully use it.
Hardmac.com
8 GB of RAM in a 2008 Macbook Pro
OWC made a very interesting discovery on the 2008 Macbook (and) Pro. These laptops were thought, and it was shown in tests, to be able to work with up to 6 GB of RAM but no more. However, it was discovered that some of them were able to fully use 8 GB of RAM. It appears that they all have in common an update EFI to modify the behavior of the Superdrive (to reduce the noise at start-up), which was released in 2009, but all the laptops that got that update do not support 8 GB of RAM. In fact, it appears that there were two updates and that the second one replaced the first without any warning and for people who had already updated, the second one didn't appear in the Software Update menu.
The following models are concerned:
13" MacBook UNibody 2.0GHz et 2.4GHz
All 15" MacBook Pro 2.4GHz
All late 2008 15" MacBook Pro 2.53GHz with Express Card
All late 2008 15" MacBook Pro 2.8GHz with Express Card
To support 8GB of RAM, the ID and Boot Rom have to be respectively MacBookPro5,1 and MBP51.007E.B05 or MacBook5,1 and MB51.007D.B03.
If you have a more recent Boot Rom, it is not a problem. Otherwise, you need to do the EFI update again manually, depending on the model, MacBook Pro EFI Firmware Update 1.8, or MacBook EFI Firmware Update 1.4.
After that, if you are running Snow Leopard 10.6.6, you will be able to put 8GB of RAM in your laptop and fully use it.