So I recently just built my own PC, monitor, keyboard, and mouse. However, the first time I tried to install Windows 10 using a USB, it said that I needed to turn off the system and restart it, which I did. Now, the screen always shows a message saying DisplayPort No Signal, before going dark. The monitor was working before so it wasn't the monitor. It also can't be the power supply, as I turned it off completely before turning it back on again. Does anyone know what's wrong?