Windows 10: Laptop monitor goes blank when connecting with an external monitor.

My laptop monitor works just fine, but when I am connecting with an external monitor, the internal monitor goes blank. In the display settings, internal display is not detected.

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blank laptop monitor

Hello Anderson, Thanks for response. When the external monitor is desconnected, the laptop monitor is blank. Awhile back, I installed a dedicated graphics card. The laptop worked fine before I installed that card. Powering on the laptop after I installed the card ,the monitor was blank. I removed the card believing the laptop would work as before. I powered on the laptop and the monitor was still blank. I then connected an external monitor and the external monitor worked fine. The laptop is an alienware M17 R4. It has both HDMI in, and HDMI out, To prove the laptop monitor is working I connected another laptop to it via the HDMI in. The monitor worked fine, mirroring the image of the other laptop. Hope Im not putting out bad info here.

 

blank laptop monitor

Why is my laptop monitor blank but external monitor is not blank

 

My external monitor screen goes blank than reappears when I move my mouse

My Windows 10 LGgram laptop is connected by HDMI to an Dell S2721 external monitor with only the external monitor display on. The external monitor screen will go blank in various situations (using Word document, doing internet searches etc.) and the screen will reappear when I move my mouse. How do I prevent the screen from going blank

Thanks for suggestions.