Why Would My Computer Screen Go Black?

When your computer monitor goes black, it could be a simple problem with the power settings or a more complex problem with the computer hardware. When you're trying to determine the cause of your display problems, start simple and work up to the more complicated problems. It helps to have extra cables and monitors on-hand; for laptops, connecting an external monitor can work both to troubleshoot the display and to use temporarily until it's fixed.

Computer Power State

The most likely problem when your computer screen goes black is that your computer or display has gone into sleep mode. Windows power settings will first kill your display after so much time of inactivity and then put the computer to sleep after a longer period of inactivity. These settings don't turn off the monitor. You can wake a sleeping display by pressing the space bar, or press the power button on your computer to wake it from sleep mode. The screen will also go black if the computer loses power.

Monitor Connections

Check the connection between the monitor and computer. If the cable has come loose or gone bad, it may cause the display to go black while you're using the computer. If the power indicator on the monitor -- usually a small light by the button -- indicates that the monitor is turned off, turn it back on; you may have bumped it. If that doesn't work, check that the power cable is securely connected to both the monitor and the outlet.

Overheating

Overheating can cause the graphics card or motherboard to stop functioning. You can check for overheating by touch or by using a system temperature monitor. If it's overheating, turn off the computer. Clear the vents of dust, and ensure they aren't obscured by walls, desks, curtains or other common household objects. If you feel comfortable doing so, open the computer and install more fans. If you're using a laptop, there's not much more you can do than keep the fans clean and avoid obscuring the vents during use.

Internal Components

If the computer boots but you're getting no display, open the computer, or take it to a repair shop, and ensure that the graphics card is seated tightly in the motherboard. If the computer isn't booting at all, the problem may be with the hard drive or RAM. Listen for beep codes when the computer starts; these codes are determined by the motherboard manufacturer. Beep codes indicate problems based on the pattern of the noise. Look up the computer manufacturer's beep codes to see what the noises may mean.

Basic Troubleshooting

When testing components, make only one change at a time to root out the precise problem. Start with the easy things, like making sure that the cables connecting the monitor and computer are secure and that both the computer and monitor are turned on. If you have extra cables around, connect the monitor with a different cable to rule out cable defect. Likewise, if there's another monitor available, connect the computer to a different monitor to conclude if the problem is with the monitor or the computer. If you're using a laptop, connect to an external monitor to see if the problem is the display or the computer.