Hello, My 2012 mac pro is showing power issues. when I press the power button, I can hear the regular click, the LED lights up but after a few seconds, I hear another click and the machine goes off then attempts to restart again but gets into a loop of restarting until I pull the power plug off. Sometimes after a few attempts it will boot up and run for a few minutes and then get into the same restart loop. Then sometimes after a few attempts the instead of booting, the fans will start to spin at full spin before powering down automatically. I have tried resetting PRAM, SMC, replaced the GPU, tried with the RAM that came with the machine but nothing changed a thing. Is this likely to be a power issue, or a logic board failure. Thanks for your help in advance.