Officially, the new trash can Mac Pro only supports up to 64GB of RAM. That’s a lot, but not necessarily enough for the performance-obsessed graphics pros and video editors that Mac Pro is aimed at.
For those that absolutely need 128GB of RAM in their Mac Pro, the memory maestros at Transcend have figured out a way to double the supposed “maximum” amount of memory in a top of the line Mac Pro.
But as with almost everything with the Mac Pro, don’t expect it to be cheap: it will cost you $2,480 to juice your Mac Pro up to that crazy extent.
Source: Transcend