1, the computer host and monitor is charged, such as no electricity, open the power wiring switch, open the power supply. And then check the motherboard and the main chassis power supply is normally charged. (It is possible that the main chassis power supply failure)
2, such as electricity, check whether the monitor is connected to the host intact, or re-plug the video cable.
3, if it does not work, check whether the video card is loose, re-plugging (to wipe the gold finger).
4, unresolved, if the conditions for a new video card to try (there may be video card failure).
5, check the memory, check whether the memory stick is loose, re-plugging (to wipe clean the gold finger).
Basically, the above simple methods, can be resolved, such as not yet, it is recommended to find a professional maintenance unit, check the motherboard.