assuming your PSU is the same like the generic ones we have here. the rated wattage is usually wrong. For example, a generic 450W PSU usually only can output around 300-350W on peak, and the voltage is not stable. When put together with some hardware consuming around half its capacity, chances that the PSU going to fail is high. And usually here, the HDD will be damaged too, or maybe another component.
Well, that's what we have here for generic cheap PSU that usually bundled with a budget case (around US$ 10-30). But I don't know about yours.
Maybe you can show us the PSU?