I previously had a setup of one SSD partitioned in two (Yosemite on first, Windows 7 on second) and the original HDD as additional storage (two HFS+ partitions). I was going through yesterday to try to clean up and make the HDD have two partitions -- one FAT and one HTS, while retaining my backups on the HTS. Long story short, for some reason my Windows install would fail to boot after these changes (despite being on a different drive from the Windows and macOS installations).

I wiped the Windows partition and have been attempting to reinstall via Bootcamp. Unfortunately, my laptop monitor has been broken since I did the first install and I think that may be my problem. I load a bootable USB and partition through Bootcamp Assistant just fine, but upon reboot to do the Windows installation, I get a momentary grey screen followed by a blank screen (monitor turns off from no signal). It does sound as though the machine is working, so my hunch is that the MiniDisplayPort drivers have not loaded but that the Windows installation is present. If it makes a difference, the monitor is running HDMI to a HDMI-to-Minidisplayport adaptor.

I think that I have ruled out the drive being un-bootable as I just used it to do a fresh macOS install on another machine. Any advice on next steps would be greatly appreciated.

  • Another bet may be that the graphics card outputs a signal the monitor does not like and therefore refulses. Mar 20, 2020 at 11:58

1 Answer 1


I can not guarantee this is going to work. Good luck!

I assume Windows is detecting your broken display and does not know the display is broken. I assume broken means you can not see anything on the display. I also assume the external display is not mirroring the broken display. If all of this is true, then the problem is: How to get Windows installed to a point where the external monitor can be set as the main display.

There is an old answer that would require you to install VirtualBox 5.2, which would be compatible with Yosemite. Ignore the update regarding an improved procedure. The following steps would need to be added to the instructions.

  • At step 23, when running the sysprep application, Choose Enter System Audit Mode instead of Enter System Out-of-Box Experience (OOBE), as shown below.

  • At step 25, after Windows starts, execute the following steps.

    1. On the external monitor, right click and select Screen resolution, as shown below.

    2. If a window similar to the one shown below appears on the external monitor, then skip to the next step. Otherwise, while holding down the option key, press the space bar. Release both keys. Next, press and release M key, followed by the cursor key. Finally, wiggle the mouse in the external monitor display, until the window appears. If the windows does not appear, use the cursor keys to move the window to the external monitor.

    3. In the window, click on the second display, then check off the box Make this my main display, as shown below. Next, click on the OK button to close the window.

    4. Execute sysprep again, but with the following settings.

  • Thank you so much. I did come across this guide and will attempt now that I have some time. Had a change of plans and am going to attempt with Windows 10 instead. Will let you know how it goes.
    – user329488
    Mar 20, 2020 at 21:28
  • I upvoted but not enough posts for it to display. In any case, thank you so much! Had some hiccups with OOBE on the initial virtual box install but can confirm that this fully worked with Windows 10. On second pass, it does not look like the display was the issue, but in fact getting the old MBP to boot to a Windows install via USB. So this fully solved. Thanks again!
    – user329488
    Mar 24, 2020 at 19:12
  • Although you can not yet upvote, you can accept the answer. This will cause a green check mark to appear. This will help see that this answer was solved. Also, you can edit the answer and add any changes or comments that might help others. Mar 24, 2020 at 23:52

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .