I've tried installing 2 x 2gb DDR2 PC2-6400 modules into an early 2008 MacBook. After installation the machine booted into a black screen, with no chime.
I tried reseating the RAM, same problem. I reinstated the old RAM (2 x 1gb DDR2 PC2-5300 modules) and the machine booted as normal, and reported the correct RAM.
Think that I had bought duff RAM, I tried putting it in my Mid/Late 2007 MacBook Pro. This machine booted well with the new RAM, and reported the RAM correctly.
As far as I can tell, both machines SHOULD be capable of supporting exactly the same RAM modules, so it has me scratching my head.
What could be wrong with the MacBook, that isn't wrong with the MacBook Pro?