Cords alone do not have the ability to regulate the voltage. You can put any (reasonable) voltage down pretty much any cable. Your PSU will simply pull the ammount of amps it requires from the mains at what ever yours is at, ~200V. For this reason if enough power is there to light the led, there is enough of a connection to power your pc. (if the pc was poor it would heat up, mealt, and burn)
Sounds like your PSU is dead. Easiest way to diagnose is to pop a spare PSU in and trying that, or put yours into a working pc.