Get your system down to the bare bones...connect nothing that can be left off. For a system to boot, all that is needed is a motherboard, ram module, video card and monitor...cpu and heatsink, plus the psu of course. No keyboard or drives should be attached.. the idea being is to get back to basics and see if it will work, if it boots without errors..then add one item at a time back until it fails. Your psu could have chosen this particular time to die or partially die on you. Look at the back of the case to be sure you did not inadvertently move the psu switch from 110 to 230.. that can happen, and the system will not have enough voltage to work properly.