Clearing the Windows 10 external monitor cache

I bought a Surface Book on day 1 of its availability, 2 years ago this month. It’s been an excellent machine. I almost never use it with the clipboard undocked so I’m not sure I’d buy another one, but it’s been good.

Recently, though, it has developed a displeasing habit of failing to recognize external monitors. For example, last week when I was at Ignite, I had to borrow Richard’s laptop to do my product demos because mine wouldn’t talk to the monitor we had available. When I got back from Ignite, it was worse– I couldn’t use an external monitor either through the Surface Dock or the built-in DisplayPort. It didn’t matter what monitor or adapter I used, either. The only way I could make an external display light up was to undock the clipboard and plug the dock connector into it.

I tried a large variety of things to fix it, including updating the firmware on the Surface Dock, reverting to an older preview build of Windows, sacrificing a chicken, and loud cursing. Nothing.

Then I posted on Reddit. Within an hour or so, a user posted a link to this thread, and I found the magic solution. I unplugged the dock, deleted HKLM\System\CurrentControlSet\Control\GraphicsDrivers\Connectivity and HKLM\System\CurrentControlSet\Control\GraphicsDrivers\Configuration, plugged the dock  back in, and boom! The external monitor now works normally.

My theory is that a bug in Windows 10 and/or the Surface dGPU driver and/or Windows Insider upgrades caused the problem. I’m not really interested in figuring out the root cause now that I know how to fix it.

Hopefully this will help future generations who may have this same issue…

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2 Comments

Filed under General Tech Stuff

2 responses to “Clearing the Windows 10 external monitor cache

  1. Sam

    this part “I unplugged the dock, deleted HKLM\System\CurrentControlSet\Control\GraphicsDrivers\Connectivity and HKLM\System\CurrentControlSet\Control\GraphicsDrivers\Configuration, plugged the dock back in, and boom! The external monitor now works normally.”

    How did you delete this file in the HKLM folder? i cant even find that folder on my surface …. please give me details as its driving me crazy now the display wont work. cheers

    • robichaux

      You’ll need to use the registry editor to look for those keys– they’re not files in the filesystem. Not to be rude, if you don’t already know how to do that, you might need to ask a friend who does know how for help to make sure nothing accidentally gets broken.

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