Hi I tried to install Windows 10 as dual boot on my iMac (late 2009) High Sierra. First I ran into this problem someone else also had here, which is unfortunately unanswered. Anyway since I couldn't use Boot Camp Assistant, I created a bootable usb stick and installed windows manually. This worked quite well.

Then when my screen went sleeping because of I was afk for too long and I woke him up suddenly the screen split into 4 parts like in the image:

So I reinstalled windows 10 but they same happened, when the screen went to sleep (restarting didn't restore normal screen).

What can I do? Does this sound like a windows problem? Or is it due the fact that I am booting it on a Mac? Is there hardware incompatibility? I mean it works fine until the screen goes sleeping. I could reinstall windows and turn off screen sleeping as fast as possible but then something will possibly trigger this again.

edit When I restart on macOS then there stays a line from this bug which disappears after the loginenter image description here

  • We have had a few people post answers asking if this is solved. If so, please make an answer as it will surely help others. If not, no worries and you can edit any new information into the post if that helps us help you.
    – bmike
    Commented Apr 11, 2020 at 21:19

1 Answer 1


this seems like a software issue. Once you are booted into macOS, try reinstalling Windows support software from Apple via BootCamp. Once it is downloaded, install it to your Windows partition. Check this out for installation help: https://support.apple.com/en-us/HT204923

The problem with doing a manual install Is that it doesn't always install necessary drivers.

If the problem continues, then try doing a power on self-test. To do this, reboot the Mac and hold "D" while it is starting up.

Good luck!

  • Are you aware that Windows 7 is that latest version that is supported under Boot Camp for this particular vintage Mac? If you want to get Windows 10 on it, it must be a manual install and usually by first installing Win7 and then upgrading to Win10.
    – Allan
    Commented Apr 11, 2020 at 22:09
  • 1
    I am completely aware. Boot Camp still downloads the latest support software which should also work for Windows 10. Another solution would be installing Windows 7 via Boot Camp and using the Media Creation tool to upgrade to Windows 10.
    – Todd
    Commented Apr 11, 2020 at 22:14
  • "...still downloads the latest support software which should also work for Windows 10" Umm...no. This is not correct. Win7 drivers ≠ Win10 drivers.
    – Allan
    Commented Apr 11, 2020 at 22:17
  • Just use the Media Creation tool to upgrade to Windows 10 after installing Windows 7 from Boot Camp.
    – Todd
    Commented Apr 11, 2020 at 22:18
  • I cannot try this at the moment because my iMac is not within reach. However, I think I tried to install some drivers without success. Maybe I didn't do correctly. Therefore can you explain how to install the support software? Commented Apr 13, 2020 at 16:01

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