Although some can see Cooler Master eXtreme Power Plus 550 W as an option if you are not going to pull 550 W from it, we can’t recommend this unit, as it burns if you try to pull its rated wattage. Its main technical problem is efficiency, between 73.2% and 77.5%, which would prevent us from recommending this unit even if it could deliver its labeled power.
But there is another problem: pricing. Costing USD 65 it is simply too expensive for what it is. For the same price you can buy an OCZ StealthXStream 500 W, which provides higher efficiency.
You see, this unit is a renamed Seventeam ST-500BAZ, a 500 W power supply that has already been discontinued by the manufacturer – no wonder it couldn’t deliver its labeled power.