Crippled from loss of displays upon restarting from alt boot drive

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Crippled from loss of displays upon restarting from alt boot drive

HI,

I Selected for restart an alt internal drive startup disk (previously tested and confirmed working) that I had cloned for a backup.

upon restarting my dual displays do not respond at all under any circumstances so I find myself crippled. They don't even flash anything. Same if I try just running one display.

I've tried every startup key command in the book including holding option, shift, C with snow leopard DVD inserted, and still nothing. I reset PRAM and my startup sound is now louder so I know that worked, also at one point I ejected a. DVD with command E, so it seems it's booting, but where did the graphics card/displays go, and how to get them back?

2008 Mac Pro, OS 10.9.2.

thanks

Mac Pro, OS X Mavericks (10.9.2)

Posted on Mar 27, 2015 11:50 PM

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Answer 1

Bejeeber

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35 points

Mar 28, 2015 10:10 AM in response to jeebs 2

Update from jeebs 2:

Next morning I try just plain old booting again for the heck of it, and it......worked...(?!). HAPPY. 🙂

It went ahead and booted from the original drive I had been using before the crisis (YAY), and now I'm very hesitant to try booting again from the backup (which is sporting an OS version I was considering reverting back to), although that backup drive has mounted and is looking fine......

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Answer 2

Mar 28, 2015 12:26 PM in response to jeebs 2

The conventional way to recover from display parameters 'out-of-bounds' is set Startup to the disk holding the System that needs to be "fixed up', then boot into Safe Mode (hold shift at Startup and you will need to enter Userid and password to proceed) and while in Safe Mode deliberately set:

System Preferences > Displays ...

... back to settings that are benign, and be sure to 'save changes'.

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Answer 3

Bejeeber

Level 1

35 points

Mar 29, 2015 5:01 PM in response to Grant Bennet-Alder

Thanks Grant. 😎

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