Apple has pushed a secret firmware update that will allow 2008 version of MacBooks and MacBokks Pro to use 8GB of RAM.
"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."
If you've one of the following affected models:
- MacBook 13.3&Prime 2.0GHz and 2.4GHz
- MacBook Pro 15&Prime 2.4GHz (All)
- MacBook Pro 15&Prime 2.53GHz model w/ExpressCard Slot (Late 2008)
- MacBook Pro 15&Prime 2.8GHz model w/ExpressCard Slot (Late 2008)
Here's how to check the Boot ROM Version in your System Profiler:
- MacBook Pros with a Model ID of MacBookPro5,1 should have a Boot ROM Version of MBP51.007E.B05.
- MacBooks with a Model ID of MacBook5,1 should have a Boot ROM version of MB51.007D.B03
- Machines with other Model IDs aren't affected and don't need an update.
If your Boot ROM version doesn't match the numbers above, download the appropriate firmware updater for your model machine and install according to the instructions:
- For MacBook Pros (MacBookPro5,1)
MacBook Pro EFI Firmware Update 1.8
- For MacBooks (MacBook5,1)
MacBook EFI Firmware Update 1.4