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#11
I agree that random reboots usually relate to a power supply issue, total output has nothing to do with it.
The Op asked for advice then doubts the good advice he recieves is true? Random reboots and power supply issues usually go hand in hand so the advice is sound.
In this case trying a different power supply is the first thing I would try, although the system working outside of the box but not inside the box might point to another problem, shorted board or loose connections, maybe try a different sata cable.