The Cooler Master Thunder 550W power supply has a maximum wattage output of 550W. This is a mid-range capacity, and should be fine as long as it is part of an equally mid-range system build. Always make sure that a purchased PSU is capable of powering your system. Remember that a higher PSU capacity does not necessarily equate to a higher wattage output and a more expensive electricity bill. In fact, you may find that a higher capacity PSU will function more efficiently than a lower capacity PSU because it is dealing with a lower percentage of its maximum load – that is, it is not being stressed to the same extent.