Now, as I've gotten older and wiser in my years I've learned a fair share about power supplies. First off that wattage numbers can lie to you. A lot of cheap power supplies like to advertise their 'peak' wattage, not what they can sustain, meaning they can't really support as many devices as you think they can. The cheap power supplies also end up being much 'noisier', meaning that they have fluctuating voltage lines. These instabilities can make a system that appears to work 99% of the time, and then crash when the voltage drops enough to make the component lack enough voltage to function properly. Another way that power supplies are made cheaper is by making them less efficient. Efficiency is judged by how much energy is lost in conversion.



Link: AMDZone