KevinSee Posted March 23, 2021 Share Posted March 23, 2021 Issue: Whenever I plug in the HDMI cable into the laptop, the laptop built-in screen will become black screen. However the external monitor is working fine. I tried mirror mode and standard mode (extended display) and both will result in black screen for the built-in laptop screen. I need to restart the laptop in order to get the built-in screen to be working again - without plugging in the HDMI cable. Once I plug in the HDMI cable, then it will become black screen again. Even I have unplugged the HDMI cable from the laptop, the black screen on the built-in monitor remains. Here is the link to the EFI: https://github.com/skevin83/Hackintosh-Dell-E7470 The EFI folder size exceeded the maximum allowed to be uploaded here. Thus I put it in GitHub. Specification Dell Latitude E7470 Laptop INTEL CORE I5-6300U 12GB DDR4 RAM 2133MHZ 256GB SSD STORAGE M.2 INTEL HD GRAPHICS 520 14" INCH HD 1366x768 I performed a fresh installation of Catalina then upgrade to Big Sur. Thanks. IORegistryExplorerResult.zip Link to comment Share on other sites More sharing options...
KevinSee Posted March 23, 2021 Author Share Posted March 23, 2021 After the laptop fell into sleep mode and wake up again. Now both external monitor and laptop screen are working fine. That's interesting. Link to comment Share on other sites More sharing options...
Moderators Jake Lo Posted March 23, 2021 Moderators Share Posted March 23, 2021 Yes I posted this some 4-5 years ago on my guide here since Sierra, not sure it affects El Capitan or not. Been too long. You could try EDID to fix it Link to comment Share on other sites More sharing options...
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