Gb != GB, those are 4GB full-width (x64) modules, making them 512MB per x8 chip, half the size of what Apple already uses in the MBP line's fully maxed out conf

Gb != GB, those are 4GB full-width (x64) modules, making them 512MB per x8 chip, half the size of what Apple already uses in the MBP line's fully maxed out configuration.