once upon a time in 2003 i was building a server and plugged one of the molex terminals from the power supply into the extension array of other molex plugs (also in the power supply)  this is before i learned the importance of cable routing...
well,  i plugged her in and within seconds the entire case was fuming white grey acrid electrical smoke from the wrappers burning off all the cables..  yeah that could have caused an explosion if the caps in the psu had taken much more of that...