If you are experiencing problems using HDMI input, suggest do the followings:
Please check below on monitor:
- Make sure the correct HDMI input is selected in OSD.
 - Turn on the monitor first then PC.
 
Please check below on PC:
- Test the monitor on a different computer with a HDMI port.
 
- Replace another HDMI cable.
 
If above steps don’t help, please contact ViewSonic Service center.