Hi,
Does it happen when you try another monitor which uses HDMI connection as well? This could be an indication of a hardware failure already but try these following steps to identify the issue.
- Connect a different monitor using HDMI connections as well and see if you'll have the same problem.
- Do a clean install of your graphics card driver.
- Uninstall anything related to your graphics card from Device Manager and in Programs and Features.
- Download and install the latest driver from the manufacturer site.
- Reboot your PC once installed.
- If the same problem will persist last step you'll need to do is to try another HDMI cable and lastly a replacement graphics card may be required already.