Power supplies may not have the glamour, nor get the attention that processors and displays receive, but they are just as vital to system operation. A failed or marginal supply can bring a system to a halt or cause intermittent operation which compromises the end product and OEM’s reputation. It’s not only outright supply failure that presents a cause for concern. A supply that is poorly designed or improperly built may degrade prematurely and cause inexplicable or misdiagnosed problems. In short, reliability is essential. Here we look at reliability in power supplies, how it’s measured and how it can be improved.