Can't boot Win 7 on my 2012 iMac anymore

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Can't boot Win 7 on my 2012 iMac anymore

Hi all,

I needed windows recently so installed it. The installation was from a windows 7 dvd i always used, and it went fine. But when it came to setting up the windows to run for the first time after the installation, the computer just rebooted. And when i tried to boot into windows it just shows the black screen with blinking dash and nothing else happens.
Something is changed and I don't know what. Maybe just the updated Mac OS X Yosemite? But i tried Mavericks also and snow leopard... I also tried to do bootcamp install and directly booting from the cd... It always installs fine but when it comes to starting it up, windows just stays on black screen. Also tried to instal windows 8. Same thing, installs fine and then when it needs to run - nothing.

What's the reason for this?

iMac, OS X Yosemite (10.10.3)

Posted on Apr 15, 2015 12:52 PM

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Answer 1

Apr 15, 2015 3:43 PM in response to Shpau

Try searching or asking in the Boot Camp discussion located here: Boot Camp

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Answer 2

Loner T

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Apr 15, 2015 3:52 PM in response to Shpau

What year/model is your iMac? If it has an AMD GPU as mentioned for the models in Boot Camp: iMac displays a black screen during installation of Windows 7 - Apple Support, you can try the associated fix. You should a USB2 device, not a USB3 device.

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Answer 3

Shpau Author

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Apr 16, 2015 1:56 AM in response to Loner T

Mine is as I said year 2012 i7 and yes it has AMD GPU. But installation is not a problem. Everything is ok during that. The problem is: after I install windows it won't start

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Answer 4

Loner T

Level 9

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Apr 16, 2015 7:40 AM in response to Shpau

Can you post the current state of disk and the CS volume from OS X Terminal?

diskutil list

diskutil cs list

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0

Sudo commands require your password, and will warn you about improper use and potential data loss, if abused.

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Answer 5

Shpau Author

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Apr 16, 2015 8:07 AM in response to Loner T

Hey, I was reading some of your previous posts about theese terminal commands, so I got the idea what can be the reason for windows not loading up. Unfortunately I erased the windows partition yesterday, so I will try to do a clean install of everything after I backup my files. If I have trouble after that, I'll let you know.

Thanks a lot in advance for sharing your knowledge!

Cheers!

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Answer 6

Shpau Author

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Apr 16, 2015 5:09 PM in response to Loner T

Ok I did the clean reinstall. Wiped out whole hdd. Installed yosemite. Opened BCA made a partition for windows. Installed windows 7 and then after the last restart when it should load the system it said: preparing desktop.... logging off... shutting down. And that was it. after the power up with alt key windows partition was visible. Selected it, tried to boot it but left just with blinking cursor on black screen.

Help please

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Answer 7

Loner T

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Apr 16, 2015 5:19 PM in response to Shpau

There are several reboots, not just one. Till you get prompted for creating a new user account, do not use the Alt/Option key. You now have a partially installed set of BC drivers. You GPU driver is most likely the one which has not been fully installed.

You have two choices.

1. Re-install Windows and wait till you see the account creation screen.

2. In OSX System Preferences -> Startup Disk -> select Bootcamp and click Restart and see if it will finish installing Windows properly.

If you are in OS X, tell me the exact AMD GPU.

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Answer 8

Shpau Author

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Apr 16, 2015 5:45 PM in response to Loner T

Yes I know about the reboots. I pass all during the installation and it finishes. I also can set the account name and computer name then when it needs to show the desktop it just says logging off and it shuts down.

and the and is AMD Radeon HD 6970M 2048 MB

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Answer 9

Loner T

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Apr 16, 2015 6:12 PM in response to Shpau

This is very confusing 2012 iMacs are

iMac (27-inch, Late 2012) - Technical Specifications

Graphics

2.9GHz
NVIDIA GeForce GTX 660M graphics processor with 512MB of GDDR5 memory
3.2GHz
NVIDIA GeForce GTX 675MX graphics processor with 1GB of GDDR5 memory
Configurable to NVIDIA GeForce GTX 680MX with 2GB of GDDR5 memory.

iMac (21.5-inch, Late 2012) - Technical Specifications

Graphics

2.7GHz
NVIDIA GeForce GT 640M graphics processor with 512MB of GDDR5 memory
2.9GHz
NVIDIA GeForce GT 650M graphics processor with 512MB of GDDR5 memory

From iMac (27-inch): AMD Radeon 6970M Video Card Replacement Program - Apple Support

iMac computers with affected video cards were sold between May 2011 and October 2012

Can I suggest you try Boot Camp: iMac displays a black screen during installation of Windows 7 - Apple Support even though it does not match your specific 2012 iMac model. Your issue is GPU related. As a test, can you try booting Windows 7 in Safe Mode (use F8/Fn-F8/Shift-F8)? If it comes up in safe mode, the generic VGA driver works, but the normal GPU driver does not.

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Answer 10

Shpau Author

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Apr 16, 2015 6:19 PM in response to Loner T

Sorry I'm an idiot. Wrong year. I'll try now with the safe mode

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Answer 11

Shpau Author

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Apr 16, 2015 6:27 PM in response to Shpau

I'm not sure if it can enter the safe mode if there is only blinking dash?

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Answer 12

Loner T

Level 9

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Apr 16, 2015 6:38 PM in response to Shpau

Much better to know it is a 2011 model, not a 2012. Thanks for clarifying. You have the iMac black screen malady afflicting AMD GPUs. Remove Windows via BCA and use the link to re-install Windows. Please post back if you run into any issues.

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Answer 13

Shpau Author

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Apr 16, 2015 7:43 PM in response to Loner T

Nothing... Still the same thing.

installs everything, i create account and then it says shutting down, although it just restarts to black screen when it tries to boot. After that I can boot it only to black screen with white dash