So why did my x850xt aiw burn its power connector to a crisp?

[jtvang125]

I checked the power connector after the machine kept beeping at me after I restarted and low and behold the connector is burnt to a crisp. I had to cut off the connector and splice on a new one. What could of cause this as it never happened before? It's a 350w power supply with 3 HDs and 2 opticals.

 

[Greenman]

Bad connections heat up under load, plug prolly wasn't all the way in.