Windows 8 and 8.1 Forums


Unlock EFI Partition

  1. #1


    Posts : 1,360
    Windows 8.1 Enterprise

    Unlock EFI Partition


    I'm having a problem connecting my laptop to an external monitor. I've encountered this problem a few times now. My external monitor will just stop working one day, and the only way I've found to fix it is to delete the keys located in the EFI partition.

    After the keys are deleted I can reset EFI in the BIOS and the monitor will then be detected by Windows. It's getting to be really annoying having to reset EFI every couple days. So, I decided to see if I could unlock the EFI partition and try to remedy this problem.

    So far I managed to set the partition as a basic data partition using SET ID=ebd0a0a2-b9e5-4433-87c0-68b6b72699c7

    Next, I assigned it a drive letter. But if I try to explore the contents I get an error saying "I don't have permission".

    Does anyone know how to assign the correct permissions??

    Click image for larger version Click image for larger version
    Last edited by ectech; 28 Dec 2013 at 10:40.

      My System SpecsSystem Spec

  2. #2


    Posts : 1,121
    Windows 8.1 x64


    Not sure the EFI partition is related to your situation. But would you describe how you are "Deleting the keys" and what type of keys they are?

    Are you running Windows 8 in the Secure Boot mode? Are you referring to the keys associated with that?
      My System SpecsSystem Spec

  3. #3


    Posts : 1,360
    Windows 8.1 Enterprise


    Quote Originally Posted by Saltgrass View Post
    Not sure the EFI partition is related to your situation. But would you describe how you are "Deleting the keys" and what type of keys they are?

    Are you running Windows 8 in the Secure Boot mode? Are you referring to the keys associated with that?
    Yes that's correct.. After having encountered this problem several times I did some research on possible fixes. Most of them include uninstalling/reinstalling the drivers for my Intel HD Graphics.. Plus disconnecting/reconnecting the HDMI cable to the monitor.. Non of those solutions fixed my issue. So I dug a little deeper and found that drivers are stored on the secure boot partition as part of start up.

    It turns out my BIOS has the option to reset or clear the secure boot keys used to digitally sign any drivers in the partition. That alone did not solve the problem, I had to choose an option which is to restore factory default for secure boot. I assume that means generate a new key. Which does the trick.

    Of course deleting the keys & resetting to factory default are becoming an inconvenience. My goal is to access the Secure Boot partition in hopes I can remedy the issue.
    Last edited by ectech; 28 Dec 2013 at 10:51.
      My System SpecsSystem Spec

  4. #4


    Posts : 1,121
    Windows 8.1 x64


    Quote Originally Posted by ectech View Post
    Yes that's correct.. After having encountered this problem several times I did some research on possible fixes. Most of them include uninstalling/reinstalling the drivers for my Intel HD Graphics.. Plus disconnecting/reconnecting the HDMI cable to the monitor.. Non of those solutions fixed my issue. So I dug a little deeper and found that drivers are stored on the secure boot partition as part of start up.
    I don't have your system, so I can't confirm or deny what you are saying. But could we look in another area? The OpRom on my Graphic cards are part of the secure boot check, but as far as I know, the monitor driver is not. It does of course have to be signed to load, but should not be effected by the Windows 8 Secure Boot. Have you tried running your system with Secure Boot turned off and did it make any difference?

    Have you tried turning off the Windows 8 "Fast Startup" option which is on the Power Options, choose what the power buttons do. This will normally effect a start from a powered down condition. If the situation depends on whether you are doing a Warm or Cold boot, it might be related to some options regarding those type of operations.

    When the monitor is recognized, what does Device Manager say about the driver? If the monitor is not recognized, does using the "Scan for hardware" in Device Manager have any effect?

    Also in Device Manager, use the View option to allow seeing hidden devices. Does your Monitor show as a greyed out item?

    With the monitor recognized and working, what settings do you show for the monitors as far as how they are configured in the Dual Monitor scenario? Are you running the same resolution in both?
      My System SpecsSystem Spec

  5. #5


    Posts : 1,360
    Windows 8.1 Enterprise


    Quote Originally Posted by Saltgrass View Post
    I don't have your system, so I can't confirm or deny what you are saying. But could we look in another area? The OpRom on my Graphic cards are part of the secure boot check, but as far as I know, the monitor driver is not. It does of course have to be signed to load, but should not be effected by the Windows 8 Secure Boot.
    I went and checked the display driver as well as the monitor driver and both have valid certificates from their respective companies.

    Quote Originally Posted by Saltgrass View Post
    Have you tried running your system with Secure Boot turned off and did it make any difference?
    Unfortunately my system doesn't have the option to turn Secure Boot off.

    Quote Originally Posted by Saltgrass View Post
    Have you tried turning off the Windows 8 "Fast Startup" option which is on the Power Options, choose what the power buttons do. This will normally effect a start from a powered down condition. If the situation depends on whether you are doing a Warm or Cold boot, it might be related to some options regarding those type of operations.
    That sounds like a great idea, I will test to see if it makes any difference.

    Quote Originally Posted by Saltgrass View Post
    Also in Device Manager, use the View option to allow seeing hidden devices. Does your Monitor show as a greyed out item?
    Currently, the external monitor is functioning normaly. So the only grayed out items are from the previous time it disconnected.

    Quote Originally Posted by Saltgrass View Post
    With the monitor recognized and working, what settings do you show for the monitors as far as how they are configured in the Dual Monitor scenario? Are you running the same resolution in both?
    Native resolution for the laptop is 1366x768. My external monitor sets the resolution to 1600x900. As far as how it's configured Windows is set to Second Screen Only.

    In conclusion, I'll need to wait until the problem arises again. Once it does I will give the "Fast Startup" option a go to see if it makes a difference.

    Thanks!!
      My System SpecsSystem Spec

  6. #6


    Posts : 1,121
    Windows 8.1 x64


    Your system may not be able to disable Secure Boot, but if it was, it would be related to enabling the CSM (Compatibility Support Module).
      My System SpecsSystem Spec

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