Hello, I've bought a 8 GB RAM upgrade for such a machine. However, it is not working. As described at http://www.everymac.com/systems/app...-2.0-aluminum-13-late-2008-unibody-specs.html and http://blog.macsales.com/9102-secret-firmware-lets-late-08-macbooks-use-8gb it should be working. If I put only one 4GB module in the MacBook, everything works fine. But if I put both 4 GB modules in the MacBook, only few seconds it can be used. After a very short while after starting, the system is freezed. No mouse pointer can be moved and so on. However, during a short period I was seen, that the system displayed the installed 8 GB RAM. Here are the data from the system (running with a 4 GB module and a 1 GB module is also working fine): Model Name: MacBook Model Identifier: MacBook5,1 Processor Name: Intel Core 2 Duo Processor Speed: 2 GHz Number of Processors: 1 Total Number of Cores: 2 L2 Cache: 3 MB Memory: 5 GB Bus Speed: 1,07 GHz Boot ROM Version: MB51.007D.B03 SMC Version (System): 1.40f2 I use OS X 10.9.1. Is there a hint how I can use 8 GB RAM with this machine?