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Posted on October 26th, 2009 by David Bayon

How to install Windows 7 on the new 27in iMac

Windows 7 on an iMac 27in

Windows 7 isn’t officially supported in Boot Camp just yet, but that doesn’t stop it working a treat most of the time. We have it installed on one of the new MacBooks in the Labs, but the gigantic 27in iMac proved to be much more problematic (we’ll have a full review of the monster in question later this week).

The problem occurs after the main Windows 7 installation has taken place. The system reboots, the Windows 7 logo circles into life and the desktop should appear – but all you get is blackness. The system is still running – press the Caps Lock key and you’ll see the light ping on – but you can’t see anything, indicating a problem with the iMac’s ATI graphics drivers.

Fear not, though. If you’ve just blown £1,350 on this beautiful beast and are now scratching your head as to why you can’t get it working, there is a workaround to crowbar Windows 7 onto it. Just connect a USB keyboard and mouse, then follow these steps:

  1. Run the Boot Camp Assistant in OS X as normal and create a partition when asked, then insert your Windows 7 disc to reboot and begin the process proper.
  2. Windows 7 requires the NTFS file system, so once in the installer just select your new partition (labelled BOOTCAMP), click on Drive options (Advanced) and choose to format it. Then select the newly formatted partition and continue.
  3. Windows 7 will begin installing, and once it gets almost to the bottom of its checklist, it’ll try to reboot. Now, if you leave it here, you’ll get so far and see the black screen. Any further attempts to reboot will bring you to the same dead end.
  4. Instead, restart and press a key to boot from the Windows 7 disc when prompted. Rather than running the installation again, choose the little option at the bottom to Repair your computer. Decline any suggestions that pop up until you see a list of options with Command Prompt at the bottom. Choose that option.
  5. At the Command Prompt, type DEL C:\WINDOWS\SYSTEM32\DRIVERS\ATIKMDAG.SYS to delete the default ATI driver, then close the window and reboot.
  6. This time, Windows should successfully initialise a more appropriate display driver, allowing you into the desktop. From here insert your OS X disc to install the relevant hardware drivers as you normally would, then run Windows update to clear up any leftovers.

And there’s a working Windows 7 installation on your new 27in iMac. Who needs official Apple support anyway?

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Posted in: Hardware, How To, Software, Windows 7


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70 Responses to “ How to install Windows 7 on the new 27in iMac ”

  1. Don Says:
    October 26th, 2009 at 8:01 pm

    Just got 2 of the 27″ iMacs today and tried to install Windows 7 to no avail. 3 hours on the phone with Apple and MS . No help. Told that a fix would be out by year end. Then I found you comments re the exact problem I was having. Problem SOLVED ! Many thanks.

  2. Michael Says:
    October 27th, 2009 at 8:40 am

    You could always use VMWare Fusion 3 that now supports a 64-bit installation of Windows 7, that’s what I’ll be doing after being a happy Fusion 1 and 2 owner!

  3. David Wright Says:
    October 27th, 2009 at 12:11 pm


    if you need decent graphics performance, for example, then Fusion isn’t going to help. Virtualisation is great for many things, but not everything, unfortunately.

  4. Steve Cassidy Says:
    October 27th, 2009 at 9:50 pm

    Fusion is completely wonderful – and there are hardware graphics accelleration passthrough capabilities, though Serge Robe, VMWare’s irrepressibly french product manager or Fusion, will admit that they are somewhat in beta. Having said that, though, if you want proper graphics then why not just get a sensible machine like a mac Pro?

  5. muck Says:
    October 28th, 2009 at 12:49 pm

    Well maybe because the cheapest Mac Pro with a half decent graphics card in(not the poor gt120) will set you back £2,058.99. Not a sensible price considering it’s just an HD 4870

  6. Nick Says:
    October 28th, 2009 at 1:04 pm

    Why on *Earth* would you soil an iMac with the uselessly over complicated nonsense that is Windows 7?

    The dock is better, the control panel sensible, there are no silly interstitial web pages blocking simple dialogs, there are not masses of useless folders jammed into your root directory you can neither delete or move – it’s a horrific OS.

    In terms of sheer simplicity OS X is astronomic units ahead of Windows. That some idiot would want to run Windows 7 on it is mind boggling.

    Running XP in a VM I can understand. On my iMac it runs very well, even full screen. Fundamentally though, I’m glad it’s only a VM.

  7. Nota Says:
    October 28th, 2009 at 8:04 pm

    Ow man! Thank you so much for your help!!! We were lost for hours after the iMac turned black! Thank god we found your tips on the net. Again, a thousand thank you!!!

  8. Hussain Andaryas Says:
    October 29th, 2009 at 7:25 am

    Actually Macs are good but when it comes to do the real job, it gives up. My imac 27 with i7 and 8 gb is coming soon. I have to install win7 because mac can not do a thing on some of the web projects and video editing projects I have. yes final cut pro is great but it gives up on persian and arabic script. leave alone that even the ms office on mac does not support fully persian.
    spent two ours at apple store and those great boys could not even figure it out why it fails even on the mac’s own office version (i don’t know what you call it).
    ok yes i love mac but until mac can do the real video editing on multi-lingual bases, i will praise windows.
    I got mac because it is cute and the screen resolution and because it has finally has a real possessor like i7 and i5 and ddr3 support.

    Mac is great but windows does more. Yes, it can get viruses but my machines never got a virus in about 15 years. I have used c prompt, dos, win3, 95, 98, 98b, win server4 2k pro, xp pro and vista. all of them buggy but all of them does the job better then man.

    My first PSs were, Quadra, mac 2, powerbook 100, powerbook duo 250, etc.
    I gave them all up when windows 2k came with multilingual support for all applications.

    As I said, mac is good and i hope in the future it really can show some work done but for now I will want to rely on win7

  9. Hussain Andaryas Says:
    October 29th, 2009 at 7:32 am

    Oh sorry, I really forgot to thank you for this article because this is the kind of article I was searching for. My English is poor but you people are smart to figure it out what I mean.
    Thank you.

  10. Vakili Says:
    October 31st, 2009 at 2:22 am

    HELP, i wrote what you are saying(DEL C:\WINDOWS\SYSTEM32\DRIVERS\ATIKMDAG.SYS) but the answer i get is could not find C:\WINDOWS\SYSTEM32\DRIVERS\ATIKMDAG.SYS please, i have been spending many many hours to install windows7 on my mac what should i do?

  11. Tim Says:
    October 31st, 2009 at 1:20 pm

    Thank you!
    I was troubleshooting for hours after someone gave me the link to your blog entry, awesome! ;)

  12. Antiseptic Says:
    October 31st, 2009 at 5:36 pm

    to 10. above: the file could be NVLDDMKM.SYS

    see this page:

  13. dame Says:
    November 1st, 2009 at 10:16 am


  14. tommaso Petrangeli Says:
    November 2nd, 2009 at 9:03 pm

    same problems… file doesnt found

  15. Sonny Dickson Says:
    November 3rd, 2009 at 7:17 am

    I ran into the black screen problem also.

    First I tried deleting the ATIKMDAG.SYS file as recommended.

    I know see the screen, but Windows puts up a dialog a few seconds later: An unexpected error has occurred. Windows 7 setup cannot continue. Click ok to reboot and restart Windows 7 setup.

  16. seemein3d Says:
    November 4th, 2009 at 1:40 am

    If it says file not found, let it boot up and go into the black screen. It actually hasn’t finished completing the installation. After that, I was able to delete the specific file. BUT after that I run into the “An unexpected error has occured.” and am told to reinstall windows… help?

  17. a.s.dawood Says:
    November 17th, 2009 at 12:05 am

    I got into the cmd of Windows 7 but I could not find either C:\WINDOWS\SYSTEM32\DRIVERS\ATIKMDAG.SYS or C:\WINDOWS\SYSTEM32\DRIVERS\NVLDDMKM.SYS
    Please help me I have an iMac from Canada or USA model what is the driver???
    If anybody can help by giving me the .sys to delete, that would be greatly appreciated. I did a DIR for all .sys files with the ATI tag but it did not get any results.

    On ,

    I also want to know if the solution is to delete C:\WINDOWS\SYSTEM32\DRIVERS\ati*.sys Does this work?

    Any reply will be greatly appreciated. Thanks.

  18. PLEASE HELP! Says:
    November 28th, 2009 at 5:11 pm

    I have tried your method but have met with nothing but failure for in the drivers directory which I browsed through there is no files entitled ATIKMDAG.SYS or NVLDDMKM.SYS

    I am on a new core i7 iMac with a x86 windows 7 ultimate attempted installation! PLEASE HELP!

  19. Gerjan Says:
    December 1st, 2009 at 6:58 pm

    First let it reboot 1 time, it will get back to the installation windows and will say:

    Completing Installation

    After that it will reboot again. Now is the time to delete the driver using the above method.

    So first let it reboot once and finish installation, after that let it reboot but choose to start the cd again.

    Good luck.

  20. Peter Says:
    December 1st, 2009 at 8:59 pm

    Many thanks guys for the solution, worked a treat.

  21. Rob Says:
    December 5th, 2009 at 8:22 pm


  22. XaX Says:
    December 6th, 2009 at 11:17 pm

    Works greate! Thanks

  23. Hansemann Says:
    December 9th, 2009 at 10:14 pm

    worked like a charms, many thanks.

  24. Jen Felicino Says:
    December 16th, 2009 at 5:08 pm

    THANK U THANK YOUUUU!! i would have died if it wasn’t this site <3

  25. patrick Says:
    December 17th, 2009 at 5:26 pm

    thank you for this! now i’ll definitely go ahead and buy an imac 27 so i can install windows 7 on it!!! thanks!

  26. Gareth Says:
    December 18th, 2009 at 7:10 pm

    Great work and solution – worked a treat!

    Note that in most cases, Windows Setup will create a “recovery” volume of 100MB at the start of the disk. This will become C: during the DOS stage of the instructions. Try the same path but D:\Windows\System32\Drivers.

    As for the what is better – Windows or Mac, depends what you want. I like the Mac hardware because its well designed, has a good out of box experience (the box is shiny, not brown cardboard) and as I get educational prices its almost reasonably priced :)

  27. Ian Says:
    December 22nd, 2009 at 12:46 pm

    Thank you, thank you! This saved me so much time!

  28. patrick Says:
    December 22nd, 2009 at 1:02 pm

    is there no way of installing windows 7 direct on this as if installing on a PC? ie without using bootcamp? ie having just windows 7 on the hard drive and no other partition?

  29. samuel Says:
    December 23rd, 2009 at 7:54 pm

    Has anyone found a solution to the ”windows installation cannot proceed” error?

  30. whitney Says:
    December 25th, 2009 at 6:35 am

    Thank you!!! You saved Christmas!!! Thank you so much!

  31. alex Says:
    December 28th, 2009 at 2:24 pm

    Thank you so much. You save me from a disappointed customer !!!!

  32. Angus Gastle Says:
    January 2nd, 2010 at 2:07 am

    That comment from Gerjan is the key to making this work. Just got Windows 7 up on my new imac. thank you!!! You made my new year!

  33. Danelgran Says:
    January 2nd, 2010 at 5:03 am

    In response to #10 above. I had the same problem because the C: drive was not availble. I tried D: and was able to delete the file

  34. Danelgran Says:
    January 2nd, 2010 at 5:30 am

    One more thing. After the initial install, your mac reboots, continues the install and the screen goes blank….DON’T DO ANYTHING! The install is still going…after a few minutes, the mac will reboot again. At that time, boot from the CD and delete the ATI file….That’s how I got it to work for me!

  35. aroch Says:
    January 5th, 2010 at 7:43 am

    Thx a lot perfectly explain!

  36. John Says:
    January 9th, 2010 at 2:31 pm

    Nick (October 28th, 2009 at 1:04 pm) wrote: “That some idiot would want to run Windows 7 on it is mind boggling.”

    That kind of uneducated comment just shows how much of an idiot *you* are. One reason I don’t want to buy a Mac is because of the elitist, arrogant and smug attitude of some Mac owners and fanboys.

  37. AJY Says:
    January 10th, 2010 at 9:02 am

    Nice work done! Have tried it successfully on my new imac, however probably because we have deleted the Ati file which was supposed to be the driver for the display, i only have the default display driver which has very limited colours and resolution. Tried to update the driver from Bootcamp CD, but went black again…… what should i do at this stage???

  38. Macheead Says:
    January 12th, 2010 at 8:52 pm

    It took me a while to find the Repair Your Computer link as when rebooted the screen went back to an installer asking again for Lanuguages/currency etc. I had to fill these in the click next and then I saw the link.

  39. willytk Says:
    January 14th, 2010 at 12:24 pm

    It worked like a charm with Win 7 Home Premium Norwegian. The only snag was I couldn’t find the \ on they keyboard so I had to “cd” my way into the drivers directory.


  40. Gareth Says:
    January 16th, 2010 at 9:16 pm

    Hi, I have really appreciated this input. I have installed W7 on my new 27″ iMac. Once i get to the black screen and go to the DOS promtp, I enter the text, hit return and the system seems to accept it. I reboot… No windows 7. It goes directly into OSX. I have 10.6.2. Its the i5 Model with 8Gb ram. Its my first MAC. any advice would be appreciated.

  41. Paul Stack Says:
    January 18th, 2010 at 4:00 pm

    Thank you so much. i have been racking my brains on this for a long time now.

    this helped a treat :)

  42. Victor DiMichina Says:
    January 19th, 2010 at 3:09 am

    Great trick. It worked for me, thanks! Trouble is that the new driver seems to blink out from time to time and I get the message “A display driver has stopped working” for the ATI Radeon family. I’m going to try and get a new driver.

  43. Bobkins Says:
    January 23rd, 2010 at 2:32 am

    I don’t know how i can do it as i don’t have an os disc, does that mean i can not install windows 7?

  44. Kristian Sørensen Says:
    February 9th, 2010 at 7:02 am

    I can help clarify a few things, while I wait for my imac to come out of black screen :)

    #28 / Patrick (Installing Windows 7 without using Bootcamp.) This is what I did. In OSX, go to Applications -> Utilities -> Disc Utility. In partitions, you can click the plus sign to create a new partition. I think Disc Utility would give clear warnings if you try to delete your main partition, but be careful not to format the whole drive with all your data. The Windows 7 installation will accept this new partition, your can ignore Bootcamp altogether. Access the Win7 installer by inserting the DVD, and holding Option (alt) as soon as your iMac turns on (before the gray apple.) If the disc symbol does not show up immidiately, have 10 seconds of patience.

    #40 / Gareth (Goes directly to Mac OSX past Win7 after installation). Remember to hold Option (alt) as soon as your iMac turns on (before the gray apple appears.) This will give you the option to boot from the Windows partition.

  45. Kristian Sørensen Says:
    February 9th, 2010 at 7:25 am

    Make sure to update the graphics drivers after installing Windows 7 – the default drivers work, but are awfully slow and do not allow for native resolution. Go to , choose your version of Windows 7 -> Radeon -> Radeon HD 4800 Series (that is, if you have the HD 4850.)

  46. Kristian Sørensen Says:
    February 10th, 2010 at 9:43 am

    #28 and others considering to install Win7 without Bootcamp. This is possible, but Apples drivers will not install if they detect that it is not a Bootcamp installation. It would probably work, but the installation won’t even start. I had to format my entire harddrive to reinstall Mac OSX and Win7, but installing Win7 via Bootcamp and then inserting the OSX disc 1 when in Win7, will start the installation of all required drivers – and it just works wonderfully :) So don’t omit Bootcamp.

  47. Jim Cool Says:
    February 20th, 2010 at 5:23 pm

    Thanks for your never ending quest to help us all.
    I also have an 27 iMac core7, and ran head first into this ATI video driver problem. Apple and Microsoft couldn’t help.
    I had tried your fix and on the first reboot of the Win 7 install, your fix didn’t work. Like the previous comments, the ATI driver wasn’t to be found and doing a directory search also showed no file labeled ATIKMDAG.SYS. Hmmmm!
    Yet another attempt and after the first reboot, I left the machine to try to figure it out for itself. It did come alive and started to update some more needed files and after it updated the registry… a second reboot started. It was during that second reboot I accessed the command prompt and this time I found that ATI driver file and deleted it. The rest of the install went as it should.

    Thanks again, now all I have to do is try to regain all the hair I lost.

  48. Kieran Moore Says:
    February 27th, 2010 at 5:29 pm

    is the path for that file in the 64 bit edition the same but with SYSTEM64 or is it 86… gah

  49. Kieran Moore Says:
    February 27th, 2010 at 6:18 pm

    ok i worked that out for myself
    but now i cant find the file to delete it.. :S

  50. barry Says:
    March 23rd, 2010 at 4:30 pm

    Thanks a lot. I now have W-7 Professional running in Bootcamp. Your tip on deleting the display driver worked like a charm to get rid of the black screen..

  51. joe Says:
    April 9th, 2010 at 3:38 pm

    this works if you get a ntfs driver for mac then go into the windows partition from mac and delete the file like that by going into the windows file then the system 32 one then to the drivers then delete the ati file (you can only do this with a ntfs read and write driver!)

  52. Carlos Mendez Says:
    April 30th, 2010 at 3:17 am

    worked very nicely. Thanks :) !!!!

  53. Andrew Says:
    May 11th, 2010 at 1:19 am

    Lifesaver! Thanks for the tip! 27 inch iMac is on 7 and OS X now!

  54. El Says:
    May 16th, 2010 at 3:32 am

    Many Thanks! it worked like a charm! I am amazed that this is a reported problem at least for 9 months and no fix was made for that.

  55. Ragamuffin Says:
    July 2nd, 2010 at 10:23 am

    Hey for those of you who get the black screen, I have a solution that can help temporarily through the installation. I edit videos and because of that i have dual monitors, through the installation i hooked up my other monitor and i could continue to see the installation through the other monitor. This is because windows 7 isnt use to having the monitor built in so it looks to the monitor out, thats why i was able to see the installation continue and restart at the appropriate time instead of mid installation. hope this helps someone

  56. ahMEmon Says:
    July 15th, 2010 at 1:15 am

    Thanks! That worked for me!

  57. Mikel Musial Says:
    August 7th, 2010 at 12:44 pm

    delete the nv_agp.sys instead works here.
    Though I have no sound on my iMac?

  58. christos Says:
    August 13th, 2010 at 1:49 pm

    Wow, this works perfectly! thanks for posting!

  59. Darin Says:
    September 9th, 2010 at 9:06 pm

    After I delete the driver and restar it comes with message that error has occured and then it ask to restart and the error comes up again. Please help!

  60. Del Says:
    September 12th, 2010 at 3:03 pm

    Thanks so much for this. Now I see both mac and windows on the startup page when I press option upon start. Problem is this: I was not able to insert the mac OS X snow leopard disk before the installation completed. How can I get the Mac files for Boot Camp onto my Windows partition?

  61. Soila Raduenz Says:
    November 13th, 2010 at 11:56 pm

    In the past I used shaving to eliminate my excess hair but it was so painful that I needed to stop. I gave shaving a try and it turned out out but was sometimes tedious. So I looked a few weeks researching the tria hair remover. I actually bought the silk’n sensepil and am absolutely happy with the final outcome. It provided me permanent hair removal at an great price tag. I highly recommend it to anyone instead of sugaring.

  62. Gabor Says:
    November 1st, 2011 at 8:28 pm

    I was at the point of giving up to install Win7 on my iMac, when I found this article. I followed Davids instructions and got beyond the black screen.
    Windows 7 now works perfectly on my late 2009 27″ iMac. Thank you

  63. Wilfred Bernardin Says:
    November 10th, 2011 at 9:23 am

    Hey hey hey, take a gadenr at what?¯ you?¯ve done

  64. Karl Says:
    November 11th, 2011 at 9:04 am

    when i press a key to boot form CD/DVD, it will instantly go into ‘Loading windows files’ or something like that. I have a new 21.5″ if that makes any difference?

  65. steve Says:
    December 18th, 2011 at 9:14 am

    nick, windows 7 isnt nonsense its actually quite useful and the taskbar is million times better than the dock, ive used both and win 7 wins hands over. windows has more games. obviously the one negative is VIRUSES so thats one area that mac has an advantage.

  66. Paulo Rocha Says:
    February 6th, 2012 at 11:01 am

    Fantastic!!!!! Works great!!!!

  67. Aslan Says:
    March 23rd, 2013 at 5:24 pm

    Your a legend. I was looking for a solution. Went to Apple official support & it was confusing. Found your blog & it worked like a charm. Thanks again

  68. Matt Says:
    April 10th, 2013 at 8:39 am

    Ragamuffin your brilliant, this is my second install and totally forgot the second monitor trick, ok gotta go I Need my windows NOW

  69. Matt Says:
    April 10th, 2013 at 10:15 am

    Don’t delete a thing just plug into a second screen and finish the install,once completed windows will work on your mac screen also.

  70. Frank Says:
    April 30th, 2013 at 12:35 pm

    Win 7 failed for me with a 512gb bootcamp partition. but worked perfectly with a 1tb Bootcamp partition. Dvd won’t work. You have to have a win 7 iso and create a usb stick from an iso image then finish bootcamp.


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