Our desktop was in sleep mode for about half a day and when we tried to wake it up by moving the mouse the monitor came on quickly, but the display lasted less than 2 seconds. After numerous times, moving mouse, pressing keyboard keys, turning monitor off, rebooting the system and that did not help. Monitor came on for about a second and it went back off. We realized by turning the monitor off and on, it would be on for about a second and back off. We tried to hook up another monitor but it was older and the plugs did not match.

So how do we know if it is the monitor or the video card?

Thanks for any info.