iMac will not boot and recovery software?

[Museo12]

Sorry for my English but I try!

I have a iMac 27 "3.1 GHz Intel Core i5 from mid 2011.12GB memory.

For a week I had problems with the image on the screen was staggered when I was working.The image flickered too. It disappeared after two restarts, and then the next problem was that the computer shut itself down after ca. 10 min of using. Sometimes I could not even login. Come to the image of the apple and the bar loaded, but then it became white and the computer rebooted. During this period I installed Il Capitan in the hope that it would solve the problems. It did not.

Now it has gone so far that I can never login. Coming to the screen for the apple and, the bar being loaded, and then it will be white. And then the computer restarts.

I have tried with wired keyboard:
Starting in Safe Mode: not working
Reset the NVRAM: not helping
Keeping alt down at startup: can select the network and to restore the hard drive, but after that nothing happens.
Keep D pressed on startup: get error code 6000D
Keep cmd + alt + r pressed at startup: the same error 6000D
Keep cmd + r / alt + r: nothing happens
Keep cmd + alt + p + r: nothing happens

Can I do anything else?

I have some files that I do not have backup. Works program like DiskWarrior and / or Boot Rescue if it´s starts from the USB stick? Which is the best?

 

[keysofanxiety]

Sorry for my English but I try!

I have a iMac 27 "3.1 GHz Intel Core i5 from mid 2011.12GB memory.

For a week I had problems with the image on the screen was staggered when I was working.The image flickered too. It disappeared after two restarts, and then the next problem was that the computer shut itself down after ca. 10 min of using. Sometimes I could not even login. Come to the image of the apple and the bar loaded, but then it became white and the computer rebooted. During this period I installed Il Capitan in the hope that it would solve the problems. It did not.

Now it has gone so far that I can never login. Coming to the screen for the apple and, the bar being loaded, and then it will be white. And then the computer restarts.

I have tried with wired keyboard:
Starting in Safe Mode: not working
Reset the NVRAM: not helping
Keeping alt down at startup: can select the network and to restore the hard drive, but after that nothing happens.
Keep D pressed on startup: get error code 6000D
Keep cmd + alt + r pressed at startup: the same error 6000D
Keep cmd + r / alt + r: nothing happens
Keep cmd + alt + p + r: nothing happens

Can I do anything else?

I have some files that I do not have backup. Works program like DiskWarrior and / or Boot Rescue if it´s starts from the USB stick? Which is the best?

From the description of your issues, especially the bit about the image on the screen being staggered, it sounds like the graphics chip failed on your iMac. This is a common issue with the Radeons on the 2011 models. Go back to Apple and they'd be able to fix it free of charge.

 

[Museo12]

Read this article may be this will help you and revert me back if you find this helpful
http://www.macworld.co.uk/news/mac/steps-take-when-your-mac-wont-start-3423817/

Thanks there are some things I have'nt tried.

Yes, it could be graphic chip problem. Or the harddrive?