Mountain Lion memory limitation tested


macrumors 68000
Original poster
Jun 30, 2011
Hi all,

After installing Mountain Lion on our "new" 12 core 2.4 Mac Pro with 128GB installed, I tested the 96GB limit that appears to have been in place since Snow Leapord (IIRC).

From the picture attached, you can see the OS recognizes the 128GB in "About This Mac", however activity monitor only registers 96 GB. From my test of running a particular program that I knew would try and used all 128 GB of RAM, I'm seeing swapping once active memory reaches 96 GB.

I guess we'll have to wait for 10.9 for >96 GB of RAM?



macrumors 65816
Oct 31, 2006
Is this a firmware imposed limitation or an OS one? If you boot Windows or Linux on it does all 128Gb get used?