content: I work in online live tech support. We have just as many people who need bottom-up support as those who don't.  "Sir, the fact that the LED didn't come on means it's a failed PSU. Unplug the PSU from everything except for AC and try that test again for me."  does so "It still didn't turn on. My boss says it's the motherboard."  "But the LED not lighting just confirmed it's the PSU."  "My boss says it's the board. I want a motherboard, it'll fix my problem." dispatches motherboard