how to run hardware test on 2012 mac pro ? OSX 10.10.4 System turns on and works, then suddenly cuts off power. This is unpredictable, sometime minutes after boot, sometime even during the boot process. First, seems the power supply is failing - resulting in such behavior. OR more serious problem with mother board. is there a hardware test for this this? how to run it? tried to press "D" on boot - just booted into system.