Yes i don't have a spare psu however I have noticed that while playing mc it doesn't shut off at all.Just went through all 9 pages and I didn't see anywhere that said that the PSU had been changed. It seemed like there was a point early on that it was going to be then it seemed attention got placed somewhere else. Are we still working with the same power supply?
We were never informed on if the 24pin was properly plugged in or not. If this isn't plugged in properly and is arcing then it will shut off after a load is put on it. MC is not very hardware intensive so it would make sense why it isn't shutting off the PC. A new PSU might be in order anyways if it's run a while like this.