Troubleshooting a desktop computer: PSU or Motherboard?

In this video I demonstrate troubleshooting procedures with an emachine personal desktop computer that is not powering on. This emachine desktop computer shuts itself down after only a few seconds. I demonstrate how to use an ATX power supply tester to correctly diagnose power problems on ATX switching power supplies. The tester model used in this video is now obsolete but here is a link for a comparative replacement: http://www.atxpowersupplies.com/ATX-Power-Supply-Tester.php Also, please note that ideally, an Earth-grounded ESD strap should be worn when working inside a computer. Additionally, medical grade gloves should be worn to prevent natural oils from the fingers contaminating any components - especially on the processor or heatsink surface. This was a rare exception to that rule as the only purpose was to power up and retrieve data from the hard drive. This desktop was disposed of following this repair.