Re: RAM: 3GB vs. 2GB?
This is what he posted again:
"I've heard that 3GB could possibly be slower than 2GB if not used in double channel."
This "double channel" business only affects three Mac systems… the Mac Pro, the Mac mini and the MacBook. I'm going to ignore the Mac Pro here because it's RAM type and configuration is something completely different.
For the Mac mini and the MacBook it is prefers matched RAM in its SODIMM slots because of the GMA950 integrated graphics processor. The rest of the architecture is not affected by matched, or unmatched for that matter, RAM. It's for the GMA950 only. The perfomance penalty for having unmatched RAM in this case is around 6-9%.
The MacBook Pro does not have this issue due to the fact that the GPU, the ATi Radeon X1600 Mobility, has 128MB (or 256MB in the case of the 2.33GHz model) of dedicated GDDR3 memory so it does not have to interact with system memory like the GMA950.
Having unmatched RAM will not affect system performance at all with an MBP, nor a 24" iMac for that matter.