This article lists the different ways the Power Macintosh G3 (Blue and White) responds when the Power button on the front panel is pushed.

The response to the front panel button varies depending upon the current state of the Power Macintosh G3:

If the system is off it turns on.
If the system is asleep it wakes up and presents the Shutdown dialog box.
If the system is on and running it presents the Shutdown dialog box.
If the system is in a hung state it powers down the system (this may take up to 7 seconds to occur).