Apple has quietly added additional build-to-order RAM options to its Quad-Core Mac Pro, now allowing users to configure new systems with either 12 GB (3 x 4 GB) or 16 GB (4 x 4 GB) of RAM. The new options using 4 GB RAM DIMMs carry significant price tags, with the 12 GB option resulting in a $1350 up charge over the base 3 GB configuration and the 16 GB option carrying an $1850 premium.
Notably, the "Memory" category description on the configuration page still refers to the Quad-Core Mac Pro as supporting only 8 GB of RAM, although the Mac Pro's technical specifications page has been revised to reflect the new 16 GB ceiling. The change almost certainly does not involve a hardware update, however, as the Quad-Core Mac Pro had already been known to support 16 GB of RAM despite Apple's original claims of an 8 GB maximum.
While a number of third-party RAM vendors have offered 16 GB RAM kits for the Quad-Core Mac Pro at vastly lower prices than Apple's new options, some customers prefer to purchase RAM directly from Apple for a variety of reasons, from the inclusion of AppleCare coverage on RAM for build-to-order machines to corporate or institutional purchasing policies.