Troubleshooting: My computer displays no video

If your computer won't display video, here's how to troubleshoot it. Please keep in mind that although your computer may display similar symptoms that prevent it from turning on, this article discusses what to do if the computer won't display video, meaning that when you press the power button:

• You may hear a startup chime
• You may hear fan or drive noise
• You may see the power light on the computer light up

If your computer does not turn on, when you press the power button:

• You won't hear a startup chime
• You won't hear any fan or drive noise
• The power indicator on the computer won't light up at all

If your computer is not responding at all, see the Troubleshooting: My computer won't turn on article instead.

If your computer won't display video but you can hear a startup chime, fans, drive noise, or you see the power light turn on, the first question is whether you have an external display attached (such as a Power Mac G4, Power Mac G5, Mac Pro or Mac mini) or if the display is built-in (such as an iMac, eMac, MacBook, MacBook Pro, iBook or PowerBook).

For external displays

Try these steps to resolve the issue:

1. Make sure that the monitor is turned on and has power. Make sure that the display's power cord is plugged into a working wall outlet, and that it's properly connected to the power adapter. (To check if the wall socket is working, plug in a lamp or other electrical device.)
2. Check that all video cable connections to the computer video port and to the monitor are properly connected.
3. Examine the pins on the video cable connector to make sure they are not bent or damaged in any way.
4. Connect a known working display (if you have an extra one available). If you see video after doing so, replace your old display.
5. Reset the computer's parameter RAM. (Click the link for instructions.)
6. On a Mac mini, reset the computer's PMU. (Click the link for instructions.) For Power Macintosh G3, Power Mac G4, or Power Mac G5 computers, check your user guide for the location of the PMU reset button on the logic board.
7. Next we're going to check to see if the computer has video when started up from a disc:
   1. Find the Install or Restore disc that came with the computer. Insert the Software Install and Restore disc into your CD/DVD drive. The disc may look something like the picture below.
      

      

       

   2. Shut down your computer.
   3. Once it's off, hold down the C key on the keyboard and start up your computer. This will start up the computer from the Software Install and Restore disc instead of your hard drive.
   4. If you see video when started up from disc, you may have corrupted software. You can use the Archive and Install feature of the Mac OS X installer to reinstall. This kind of installation gives you a fresh version of Mac OS X, but you don't lose any data from the computer as your old information is all archived.
8. If you tried all of the steps above and the computer still won't display video, contact Apple technical support (1-800-APL-CARE in the U.S.) or take your computer to your local Apple Store or Apple Authorized Service Provider (AASP) for diagnosis.

For built-in displays

Try these steps to resolve the issue:

1. Make sure that the power cord is plugged into a working wall outlet, and that it's properly connected to the power adapter. (To check if the wall socket is working, plug in a lamp or other electrical device.)
2. Make sure that the power adapter is properly connected to the power port on the back of the computer.
3. Reset the computer's parameter RAM. (Click the link for instructions.)
4. On an iBook or PowerBook, reset the computer's PMU. (Click the link for instructions.)
5. Next we're going to check to see if the computer has video when started up from a disc:
   1. Find the Install or Restore disc that came with the computer. Insert the Software Install and Restore disc into your CD/DVD drive. The disc may look something like the picture below.
      

      

       

   2. Shut down your computer.
   3. Once it's off, hold down the C key on the keyboard and start up your computer. This will start up the computer from the Software Install and Restore disc instead of your hard drive.
   4. If you see video when started up from disc, you may have corrupted software. You can use the Archive and Install feature of the Mac OS X installer to reinstall. This kind of installation gives you a fresh version of Mac OS X, but you don't lose any data from the computer as your old information is all archived.
6. If you tried all of the steps above and the computer still won't display video, contact Apple technical support (1-800-APL-CARE in the U.S.) or take your computer to your local Apple Store or Apple Authorized Service Provider (AASP) for diagnosis.