Ah, I break my 1337 status to answer this
Don't get me wrong, I'm happy to help but sad to see my 1337 status fade away....
Suppose your voltage converter was rated at 20 watts. Suppose you plugged in a 110v brick power supply that consumed 30 watts.
I'd expect the converter to start overheating because it's overloaded. A good portion of that heat will flow into the brick power supply plugged into it.
The internal resistance of the brick power supply will begin to drop as it heats up. The brick power supply will want even more watts from the converter which is already overloaded and overheating.
This vicious cycle continues until something melts down or catches fire.
Brick power supply = the type where the AC pins come out of the cube that holds the transformer and rectifier.
Morale of the story. I'd buy a 1000w converter knowing it would safely handle anything hpc related I plugged into it.