I have a Mac Pro 5,1 (mid 2010) with 2 x hex processors and 64 GB RAM running OS 10.10.4. I have been trying to use BOOTCAMP to load Win7 on a separate 1 TB HD. However, every time I try to do so the screen goes black and nothing happens. I was able to load Win7 with OS 10.7, but when I reinstalled the other HDs, every time I tried to launch BOOTCAMP (holding down the options key) the screen again went black and I had to do a hard reboot. Any help?