Bought a 2GB stick of ram for my girlfriend to raise her laptop up to the limit of 3GB total. Turns out her model only accepts 2GB total. Won't even boot with 3GB. It's a fucking core duo, why wouldn't it take up to 4GB, even if it only USES 3GB like the newer models. Probably should return it and save 15$ or so.
Your MBP was introduced while Apple was still on 10.4 with limited 64 bit addressing and the only 64 bit library was libSystem. Thus 4 gbs while readable and usable was only really used in higher end systems like the Mac Pro that had apps that were written to use the extra memory efficiently.
I'm saying though it has a duo in it, it wasn't released when 4 gbs of Ram would be a usual thing. The two newest OS from MS and Apple both support 64 bit architecture and are far more RAM hungry (though OS X less so to an extent) thus 4 gbs is a desirable thing to have for a majority of the population.
If you need more performance Puffer, install a 7200 RPM drive. It's like night and day on my Macbook. I went from a 80 gigabyte 5400 RPM drive to a 200 gigabyte 7200 RPM drive with more cache and my system flies. A majority of the population doesn't care about Ram, a majority of the enthusiasts population does.
Yep...I still run into machines that can't accept more than 1GB which sucks when trying to get them to replace the sucker versus upgrading what they have. The OS is irrelevant if the chipset can't handle it.
