What is the button on power supply of the Dell Optiplex 760 workstation for? There is a small button near LED power indicatior - seems to do nothing when pressed.
It's called the Built-In Self-Test (BIST) for the power supply. The BIST can be used to isolate and troubleshoot power failures throughout the system.
Here is a video from Dell about it: https://www.youtube.com/watch?v=udGOe7LQJEI