how do i know what power supply i have in my pc



 
According to the TH PSU tier rating, the 550W "second gen" version of that PSU is a tier 4, meaning:

"Built down to a low price. Not exactly the most stable units ever created. Very basic safety circuitry or even thin gauge wiring used. Not for gaming rigs or overclocking systems of any kind. Avoid unless your budget dictates your choice."