I'm not in a position to test this as I don't have the ram but I am really curious if this would work. I don't need this much ram I'm just curious. With the ability to upgrade 4,1 and 5,1 cMP to use x5690 cpu's the amount of ram the CPU can handle is well over 250gb according to intel arc. The 16gb 1333 ram sticks you can get for Mac pros are pc3-10600 ram. You can get 1333 speed pc3-10600 ram in 32gb modules. Why would the Mac Pro 4,1 (when flashed to 5,1) and 5,1 models not recognise the 32gb modules when they are the speed and configuration as the 16gb sticks just more memory? Would a 32gb stick draw too much power? Factoring in that you can get 32gb sticks at 1333 speeds for the 6,1.