I recently received my new late 2013 Mac Pro. Shortly after getting it I installed Windows 8.1 and installed the AMD Catalyst video drivers. Within the driver it recognized my GPUs as FirePro D300s, so I assume it is the correct driver for Windows. I turned on Crossfire, and started a game that supports Crossfire. I monitored the temperature of the CPU and GPUs and by the time the GPUs reached 85 degrees the computer crashed and went to the blue screen equivalent in Windows 8. It managed to reboot correctly, I immediately turned off Crossfire in the video driver. Since then there have been problems. Three times now while booting Mac OS the computer hangs on the boot screen with the grey apple logo in the center, there is a rectangle of multi-colour artifacts in the top left corner which requires a hard reboot. I just ran the Luxmark GPU test "room" on interactive which is an Open CL benchmark that maxes out the load on both GPUs and runs indefinitely. The temperature of the GPUs reached 81 degrees after 1200 seconds and the program "quit unexpectedly". I installed Windows and had the computer crash the day after I got it so there wasn't any time to compare before and after the crash. I was hoping that the issues in Mac OS were software related as a lot of people with the nMP have reported graphical problems related to the current version of Mavericks. I ran Luxmark to see if that was so, I figured if the program didn't crash that it was unlikely that the problem was hardware. When I run the Apple diagnostics tool it reports that everything is fine. I haven't contacted Apple about this yet. I have a 3 year Applecare plan. Can anyone here comment on this or recommend what I should do about it?