Both Screens on my MAC Pro only 1 year old goes black after a normal startup.
My MAC Pro boots up the in 1-3 minutes both scrteens go black. I can get the screens back temporarily by a hard boot.
Mac Pro, OS X Mountain Lion (10.8.2)
It sounds like your video card may be failing. You might want to run the Apple Hardware Test for Mountain Lion:
Use Apple Hardware Test for Mountain Lion:
- Open the Help Viewer’s Action pop-up menu (looks like a gear) and choose Print to print these instructions.
- Disconnect all external devices except the keyboard, mouse, display, and speakers. If you have an Ethernet cable or external DVD drive, disconnect them.
- Restart your computer, holding down the D key while the computer restarts.After your computer restarts, you should see the Apple Hardware Test chooser screen. If you don’t, Apple Hardware Test may not be available on your computer. You may be able to start Apple Hardware Test from the Internet. Reconnect your computer to the network, and then restart your computer while holding down both the Option and D keys.
- When the Apple Hardware Test chooser screen appears, select the language you want to use, and then press the Return key or click the right arrow button.
- When the Apple Hardware Test main screen appears (after about 45 seconds), follow the onscreen instructions.