"In this article we discuss the one component your whole computer
depends on: the Power Supply Unit. Any computer, no matter how perfectly
planned, prepared or assembled, will fail to boot, sputter, smoke and
eventually die if connected to an inadequate, weak or just plain faulty
power supply. Picking a decent power supply isn’t much of a science;
however, knowing what voltages run through your computer is, and knowing
it will come in handy once you start actually repairing, as it might
indicate what exactly went wrong with the powersupply."