I am running 8 BG of 1333 RAM on my 2009 MacBook without it giving me a moment's problem. I am running the same 8 GB of RAM in this October 2008 MacBook Pro, (15.4 inch). Both seem to work just fine. However, when I tried to install the same 8 GB RAM into a 2010 Unibody MacBook, all it would to is whistle when I tried to boot it up. To me it's weird that a newer Mac won't run the newer RAM, but the older ones will. Does anyone have an explanation for this phenomenon?
The reason this MB Pro is running the 1333 RAM is because I switched its 8 GB of 1067 RAM into the 2010 MacBook. The MacBook is running 10.6 and the Pro is running 10.7.