While we've officially confirmed that the Nvidia chipset in the new MacBooks and MacBook Pros can theoretically support up to 8GB of RAM, Apple says the capacities for each top out at 4GB. Turns out, the actual number is right there in the middle—chip supplier Ramjet has tested and officially confirmed that the new MacBooks can support 6GB RAM via one 2GB module and one 4GB module. But why not eight?
According to the rep I spoke to, Ramjet's tests and previous experiences by others have shown that 8GB of RAM in a notebook throws OS X into fits, making it unstable for actual use. Ramjet claims though that 6GB is a screamer—utilising a fresh new 4GB 1066 SO-DIMM paired with a 2GB; the performance gained by having an extra two gigs negates the performance loss that tends to follow from having an unmatched pair of differently sized modules. Sadly, that combo will set you back around $US675 at Ramjet ($US600 for the 4GB module alone). But it's possible.