Every once in a while, a blip on the radar comes up, letting us know that there’s something not quite right in our little corner of the Mac Universe. This time around, it came in the form of Tweets directed to us, as well as in posting in popular Mac forums.
As it turns out, several other memory vendors—along with some Late 08 MacBook/MacBook Pro users—have laid claim to these machines working with 8GB of RAM. This was contradictory to our testing in December 2009 which quite clearly showed that while these models recognized a full 8GB, if an application addressed more than 6GB, the system would slow down significantly.
The results were exactly the same as in 2009, lending credence to our conclusions, but the sheer number of claims to the contrary led us to continue searching—and the trail ended at Apple.
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.
The practical upshot of all this is that if you installed the EFI Update when it first came out, like we did, you would have gotten the old code, which meant your computer would only address 6GB properly. Those who didn’t upgrade until after Apple changed the updater got the newer firmware, which allowed proper addressing of 8GB.
Once we manually installed the “updated” version of the EFI Firmware in our test machines, they were able to address 8GB normally, without any crashing or slowdowns.