Power Macintosh G3 (Blue and White): Support for Non-USB Displays
The Power Macintosh G3 has both ADB and USB connectors on it to ensure compatibility with previous Apple displays which relied on ADB for full functionality.
In some cases you may need the video adapter to connect a Macintosh style video cable on the display to the VGA style connector on the video card. The adapter is included in the Accessory Kit of certain Apple displays.