How to use an iMac with external monitor as the only display (and the iMac screen turned off)?

[ButWhyY]

I have an iMac (M1, 2021) with black horizontal lines on the screen.
(https://forums.macrumors.com/threads/imac-m1-2021-display-issue.2423630/)

I have connected it to a LG FHD monitor through USB-C Digital AV Multiport Adapter.
How do I use the iMac with the monitor as the only display and the iMac screen turned off.
So far, the only way I found is to dim the display to lowest brightness.

Please advise, thanks in advance.

 

[Significant1]

Try SwitchResX
https://www.madrau.com/
I have the opposite problem. I have an external monitor, that I only want to use when needed. But macOS detects it even when powered off. The only solution is SwitchResX or physically disconnect the cable.

 

[Nguyen Duc Hieu]

I have an iMac (M1, 2021) with black horizontal lines on the screen.
(https://forums.macrumors.com/threads/imac-m1-2021-display-issue.2423630/)

I have connected it to a LG FHD monitor through USB-C Digital AV Multiport Adapter.
How do I use the iMac with the monitor as the only display and the iMac screen turned off.
So far, the only way I found is to dim the display to lowest brightness.

Please advise, thanks in advance.

Turn off iMac main screen while working on external

I have an external display on my iMac and I would like to work only on the external display and turn off/disable the iMac one, just like the "clamshell mode" on a Macbook for example. It works with

apple.stackexchange.com

GitHub - waydabber/BetterDisplay: Unlock your displays on your Mac! Flexible HiDPI scaling, XDR/HDR extra brightness, virtual screens, DDC control, extra dimming, PIP/streaming, EDID override and lots more!

Unlock your displays on your Mac! Flexible HiDPI scaling, XDR/HDR extra brightness, virtual screens, DDC control, extra dimming, PIP/streaming, EDID override and lots more! - waydabber/BetterDisplay

github.com

 

[johnrak]

I tried switchresx but even if I disable the internal display and lower its brightness there is a dim light on the screen. Is there any way to turn it off completely when using an external display?