VGA Mode at Booting (Low Resolution)
Have you installed the wrong drivers? You need to download the last version for your video card.
Is your monitor turned on? Is your monitor plugged into the right Video output? Is the mode of your monitor correctly selected?
Verify the connections and the quality of your cables.
You maybe have set up your video card into a mode that your monitor cannot handle (higher resolution, bigger FPS).
Shut your system down, boot into low resolution mode, reset your video card to the correct settings.
Black Screen can also inform you about CPU/GPU dead. In this case, you can verify by plugging USB and see if they are powered. In this case, please create a new Ticket and inform us about your tests and troubleshooting.
Screen goes and comes back
This issue can be related to overheating. Please verify your system is setup in the correct way for the heat to be dissipated.
Dead pixels are related to displays issue. If you change your display you will not have them anymore. Verify your monitor's warranty.
If you see bad images or artefacting on your screen, this can be related to 2 main problems:
1: Have you installed the wrong drivers? You need to download the last version for your video card.
2: You still have the issue? The Video card might using bad RAM. You can change the RAM and if this is not solving the problem, verify the Memory Troubleshooting Page.